diff --git a/src/app/modules/bounce/bounce.service.ts b/src/app/modules/bounce/bounce.service.ts
index fa31c17aba..e78b4dbc44 100644
--- a/src/app/modules/bounce/bounce.service.ts
+++ b/src/app/modules/bounce/bounce.service.ts
@@ -10,6 +10,7 @@ import {
   ResultAsync,
 } from 'neverthrow'
 
+import { hasProp } from '../../../shared/util/has-prop'
 import {
   BounceType,
   IBounceSchema,
@@ -25,7 +26,6 @@ import { EMAIL_HEADERS, EmailType } from '../../services/mail/mail.constants'
 import MailService from '../../services/mail/mail.service'
 import { SmsFactory } from '../../services/sms/sms.factory'
 import { transformMongoError } from '../../utils/handle-mongo-error'
-import { hasProp } from '../../utils/has-prop'
 import { PossibleDatabaseError } from '../core/core.errors'
 import { getCollabEmailsWithPermission } from '../form/form.utils'
 import * as UserService from '../user/user.service'
diff --git a/src/app/modules/myinfo/myinfo.util.ts b/src/app/modules/myinfo/myinfo.util.ts
index 6f3febbaee..5c5a05b9dd 100644
--- a/src/app/modules/myinfo/myinfo.util.ts
+++ b/src/app/modules/myinfo/myinfo.util.ts
@@ -6,6 +6,7 @@ import { err, ok, Result } from 'neverthrow'
 import { v4 as uuidv4, validate as validateUUID } from 'uuid'
 
 import { types as myInfoTypes } from '../../../shared/resources/myinfo'
+import { hasProp } from '../../../shared/util/has-prop'
 import {
   AuthType,
   BasicField,
@@ -16,7 +17,6 @@ import {
   MapRouteError,
 } from '../../../types'
 import { createLoggerWithLabel } from '../../config/logger'
-import { hasProp } from '../../utils/has-prop'
 import { DatabaseError, MissingFeatureError } from '../core/core.errors'
 import {
   AuthTypeMismatchError,
diff --git a/src/app/modules/spcp/spcp.util.ts b/src/app/modules/spcp/spcp.util.ts
index fde8713544..3aba24bbe6 100644
--- a/src/app/modules/spcp/spcp.util.ts
+++ b/src/app/modules/spcp/spcp.util.ts
@@ -3,6 +3,7 @@ import crypto from 'crypto'
 import { StatusCodes } from 'http-status-codes'
 import { err, ok, Result } from 'neverthrow'
 
+import { hasProp } from '../../../shared/util/has-prop'
 import {
   AuthType,
   BasicField,
@@ -11,7 +12,6 @@ import {
   SPCPFieldTitle,
 } from '../../../types'
 import { createLoggerWithLabel } from '../../config/logger'
-import { hasProp } from '../../utils/has-prop'
 import { MissingFeatureError } from '../core/core.errors'
 import {
   AuthTypeMismatchError,
diff --git a/src/public/modules/forms/helpers/CsvMergedHeadersGenerator.js b/src/public/modules/forms/helpers/CsvMergedHeadersGenerator.ts
similarity index 63%
rename from src/public/modules/forms/helpers/CsvMergedHeadersGenerator.js
rename to src/public/modules/forms/helpers/CsvMergedHeadersGenerator.ts
index 622e95af67..9e148e92f2 100644
--- a/src/public/modules/forms/helpers/CsvMergedHeadersGenerator.js
+++ b/src/public/modules/forms/helpers/CsvMergedHeadersGenerator.ts
@@ -1,21 +1,40 @@
-const moment = require('moment-timezone')
-const keyBy = require('lodash/keyBy')
-const { CsvGenerator } = require('./CsvGenerator')
-const { getResponseInstance } = require('./response-factory')
-
-/**
- * @typedef {{
- *    _id: string,
- *    question: string,
- *    answer?: string,
- *    answerArray?: string[],
- *    fieldType: string,
- *    isHeader?: boolean,
- * }} DisplayedResponse
- */
-
-class CsvMergedHeadersGenerator extends CsvGenerator {
-  constructor(expectedNumberOfRecords, numOfMetaDataRows) {
+import keyBy from 'lodash/keyBy'
+import moment from 'moment-timezone'
+
+import { DisplayedResponseWithoutAnswer } from '../../../../types/response'
+
+import { Response } from './csv-response-classes'
+import { CsvGenerator } from './CsvGenerator'
+import { getResponseInstance } from './response-factory'
+
+type KeyedResponse = { [fieldId: string]: Response }
+
+type UnprocessedRecord = {
+  created: string
+  submissionId: string
+  record: KeyedResponse
+}
+
+type SubmissionRecord = {
+  record: DisplayedResponseWithoutAnswer[]
+  created: string
+  submissionId: string
+}
+
+export class CsvMergedHeadersGenerator extends CsvGenerator {
+  hasBeenProcessed: boolean
+  hasBeenSorted: boolean
+  fieldIdToQuestion: Map<
+    string,
+    {
+      created: string
+      question: string
+    }
+  >
+  fieldIdToNumCols: Record<string, number>
+  unprocessed: UnprocessedRecord[]
+
+  constructor(expectedNumberOfRecords: number, numOfMetaDataRows: number) {
     super(expectedNumberOfRecords, numOfMetaDataRows)
 
     this.hasBeenProcessed = false
@@ -28,25 +47,25 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
   /**
    * Returns current length of CSV file excluding header and meta-data
    */
-  length() {
+  length(): number {
     return this.unprocessed.length
   }
 
   /**
-   *
-   * @param {Object} decryptedContent
-   * @param {DisplayedResponse[]} decryptedContent.record
-   * @param {string} decryptedContent.created
-   * @param {string} decryptedContent.submissionId
+   * Extracts information from input record, rearranges record and then adds an UnprocessedRecord to this.unprocessed
+   * @param decryptedContent
+   * @param decryptedContent.record
+   * @param decryptedContent.created
+   * @param decryptedContent.submissionId
+   * @throws Error when trying to convert record into a response instance. Should be caught in submissions client factory.
    */
-  addRecord({ record, created, submissionId }) {
+  addRecord({ record, created, submissionId }: SubmissionRecord): void {
     // First pass, create object with { [fieldId]: question } from
     // decryptedContent to get all the questions.
     const fieldRecords = record.map((content) => {
       const fieldRecord = getResponseInstance(content)
       if (!fieldRecord.isHeader) {
         const currentMapping = this.fieldIdToQuestion.get(fieldRecord.id)
-
         // Only set new mapping if it does not exist or this record is a later
         // submission.
         // Might need to differentiate the question headers if we allow
@@ -77,28 +96,16 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
     })
   }
 
-  /**
-   * Extracts the string representation from an unprocessed record.
-   * @param {Object} unprocessedRecord
-   * @param {string} fieldId
-   * @returns {string}
-   */
-  _extractAnswer(unprocessedRecord, fieldId, colIndex) {
-    const fieldRecord = unprocessedRecord[fieldId]
-    if (!fieldRecord) return ''
-    return fieldRecord.getAnswer(colIndex)
-  }
-
   /**
    * Process the unprocessed records by creating the correct headers and
    * assigning each answer to their respective locations in each response row in
    * the csv data.
    */
-  process() {
+  process(): void {
     if (this.hasBeenProcessed) return
 
     // Create a header row in CSV using the fieldIdToQuestion map.
-    let headers = ['Reference number', 'Timestamp']
+    const headers = ['Reference number', 'Timestamp']
     this.fieldIdToQuestion.forEach((value, fieldId) => {
       for (let i = 0; i < this.fieldIdToNumCols[fieldId]; i++) {
         headers.push(value.question)
@@ -109,26 +116,44 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
     // Craft a new csv row for each unprocessed record
     // O(qn), where q = number of unique questions, n = number of submissions.
     this.unprocessed.forEach((up) => {
-      let createdAt = moment(up.created).tz('Asia/Singapore')
-      createdAt = createdAt.isValid()
+      const createdAt = moment(up.created).tz('Asia/Singapore')
+      const formattedDate = createdAt.isValid()
         ? createdAt.format('DD MMM YYYY hh:mm:ss A')
-        : createdAt
-      let row = [up.submissionId, createdAt]
-      for (let [fieldId] of this.fieldIdToQuestion) {
+        : createdAt.toString() // just convert to string if given date is not valid
+      const row = [up.submissionId, formattedDate]
+
+      this.fieldIdToQuestion.forEach((_question, fieldId) => {
         const numCols = this.fieldIdToNumCols[fieldId]
         for (let colIndex = 0; colIndex < numCols; colIndex++) {
           row.push(this._extractAnswer(up.record, fieldId, colIndex))
         }
-      }
+      })
       this.addLine(row)
     })
     this.hasBeenProcessed = true
   }
 
+  /**
+   * Extracts the string representation from a field response
+   * @param unprocessedRecord
+   * @param fieldId
+   * @param colIndex
+   * @returns string representation of unprocessed record
+   */
+  private _extractAnswer(
+    unprocessedRecord: KeyedResponse,
+    fieldId: string,
+    colIndex: number,
+  ): string {
+    const fieldRecord = unprocessedRecord[fieldId]
+    if (!fieldRecord) return ''
+    return fieldRecord.getAnswer(colIndex)
+  }
+
   /**
    * Sorts unprocessed records from oldest to newest
    */
-  sort() {
+  sort(): void {
     if (this.hasBeenSorted) return
     this.unprocessed.sort((a, b) => this._dateComparator(a.created, b.created))
     this.hasBeenSorted = true
@@ -138,8 +163,8 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
    * Add meta-data as first three rows of the CSV. If there is already meta-data
    * added, it will be replaced by the latest counts.
    */
-  addMetaDataFromSubmission(errorCount, unverifiedCount) {
-    let metaDataRows = [
+  addMetaDataFromSubmission(errorCount: number, unverifiedCount: number): void {
+    const metaDataRows = [
       ['Expected total responses', this.expectedNumberOfRecords],
       ['Success count', this.length()],
       ['Error count', errorCount],
@@ -151,9 +176,9 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
 
   /**
    * Main method to call to retrieve a downloadable csv.
-   * @param {string} filename
+   * @param filename name of csv file
    */
-  downloadCsv(filename) {
+  downloadCsv(filename: string): void {
     this.sort()
     this.process()
     this.triggerFileDownload(filename)
@@ -161,10 +186,10 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
 
   /**
    * Comparator for dates
-   * @param string firstDate
-   * @param string secondDate
+   * @param firstDate
+   * @param secondDate
    */
-  _dateComparator(firstDate, secondDate) {
+  private _dateComparator(firstDate: string, secondDate: string): number {
     // cast to Asia/Singapore to ensure both dates are of the same timezone
     const first = moment(firstDate).tz('Asia/Singapore')
     const second = moment(secondDate).tz('Asia/Singapore')
@@ -178,5 +203,3 @@ class CsvMergedHeadersGenerator extends CsvGenerator {
     }
   }
 }
-
-module.exports = CsvMergedHeadersGenerator
diff --git a/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.js b/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.js
deleted file mode 100644
index 5b06db10ad..0000000000
--- a/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.js
+++ /dev/null
@@ -1,11 +0,0 @@
-const Response = require('./Response.class')
-
-module.exports = class ArrayAnswerResponse extends Response {
-  getAnswer() {
-    return this._data.answerArray.join(';')
-  }
-
-  get numCols() {
-    return 1
-  }
-}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.ts b/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.ts
new file mode 100644
index 0000000000..f77e486541
--- /dev/null
+++ b/src/public/modules/forms/helpers/csv-response-classes/ArrayAnswerResponse.class.ts
@@ -0,0 +1,20 @@
+import { ArrayResponse } from '../../../../../types/response'
+
+import { Response } from './Response.class'
+
+export class ArrayAnswerResponse extends Response {
+  private response: ArrayResponse
+
+  constructor(responseData: ArrayResponse) {
+    super(responseData)
+    this.response = responseData
+  }
+
+  getAnswer(): string {
+    return this.response.answerArray.join(';')
+  }
+
+  get numCols(): number {
+    return 1
+  }
+}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/Response.class.js b/src/public/modules/forms/helpers/csv-response-classes/Response.class.js
deleted file mode 100644
index c10cb850f4..0000000000
--- a/src/public/modules/forms/helpers/csv-response-classes/Response.class.js
+++ /dev/null
@@ -1,21 +0,0 @@
-module.exports = class Response {
-  constructor(responseData) {
-    this._data = responseData
-  }
-
-  get id() {
-    return this._data._id
-  }
-
-  /**
-   * Gets the CSV header.
-   * @returns {string}
-   */
-  get question() {
-    return this._data.question
-  }
-
-  get isHeader() {
-    return this._data.isHeader
-  }
-}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/Response.class.ts b/src/public/modules/forms/helpers/csv-response-classes/Response.class.ts
new file mode 100644
index 0000000000..9f2c1d62bc
--- /dev/null
+++ b/src/public/modules/forms/helpers/csv-response-classes/Response.class.ts
@@ -0,0 +1,29 @@
+import { DisplayedResponseWithoutAnswer } from '../../../../../types/response'
+
+export abstract class Response {
+  private data: DisplayedResponseWithoutAnswer
+
+  constructor(responseData: DisplayedResponseWithoutAnswer) {
+    this.data = responseData
+  }
+
+  get id(): string {
+    return this.data._id
+  }
+
+  /**
+   * Gets the CSV header.
+   * @returns {string}
+   */
+  get question(): string {
+    return this.data.question
+  }
+
+  get isHeader(): boolean {
+    return this.data.isHeader ?? false
+  }
+
+  abstract get numCols(): number
+
+  abstract getAnswer(colIndex?: number): string
+}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.js b/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.js
deleted file mode 100644
index fecb3d1d7e..0000000000
--- a/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.js
+++ /dev/null
@@ -1,11 +0,0 @@
-const Response = require('./Response.class')
-
-module.exports = class SingleAnswerResponse extends Response {
-  getAnswer() {
-    return this._data.answer
-  }
-
-  get numCols() {
-    return 1
-  }
-}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.ts b/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.ts
new file mode 100644
index 0000000000..f495544e3f
--- /dev/null
+++ b/src/public/modules/forms/helpers/csv-response-classes/SingleAnswerResponse.class.ts
@@ -0,0 +1,20 @@
+import { SingleResponse } from '../../../../../types/response'
+
+import { Response } from './Response.class'
+
+export class SingleAnswerResponse extends Response {
+  private response: SingleResponse
+
+  constructor(responseData: SingleResponse) {
+    super(responseData)
+    this.response = responseData
+  }
+
+  getAnswer(): string {
+    return this.response.answer
+  }
+
+  get numCols(): number {
+    return 1
+  }
+}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.js b/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.js
deleted file mode 100644
index 4352169a40..0000000000
--- a/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.js
+++ /dev/null
@@ -1,15 +0,0 @@
-const Response = require('./Response.class')
-
-module.exports = class TableResponse extends Response {
-  getAnswer(colIndex) {
-    // Leave cell empty if number of rows is fewer than the index
-    if (colIndex >= this._data.answerArray.length) {
-      return ''
-    }
-    return this._data.answerArray[colIndex].join(';')
-  }
-
-  get numCols() {
-    return this._data.answerArray.length
-  }
-}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.ts b/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.ts
new file mode 100644
index 0000000000..cd62ec6b24
--- /dev/null
+++ b/src/public/modules/forms/helpers/csv-response-classes/TableResponse.class.ts
@@ -0,0 +1,24 @@
+import { NestedResponse } from '../../../../../types/response'
+
+import { Response } from './Response.class'
+
+export class TableResponse extends Response {
+  private response: NestedResponse
+
+  constructor(responseData: NestedResponse) {
+    super(responseData)
+    this.response = responseData
+  }
+
+  getAnswer(colIndex: number): string {
+    // Leave cell empty if number of rows is fewer than the index
+    if (colIndex >= this.response.answerArray.length) {
+      return ''
+    }
+    return this.response.answerArray[colIndex].join(';')
+  }
+
+  get numCols(): number {
+    return this.response.answerArray.length
+  }
+}
diff --git a/src/public/modules/forms/helpers/csv-response-classes/index.js b/src/public/modules/forms/helpers/csv-response-classes/index.js
deleted file mode 100644
index 837b2c4d38..0000000000
--- a/src/public/modules/forms/helpers/csv-response-classes/index.js
+++ /dev/null
@@ -1,3 +0,0 @@
-module.exports.SingleAnswerResponse = require('./SingleAnswerResponse.class')
-module.exports.ArrayAnswerResponse = require('./ArrayAnswerResponse.class')
-module.exports.TableResponse = require('./TableResponse.class')
diff --git a/src/public/modules/forms/helpers/csv-response-classes/index.ts b/src/public/modules/forms/helpers/csv-response-classes/index.ts
new file mode 100644
index 0000000000..b3ac7f159c
--- /dev/null
+++ b/src/public/modules/forms/helpers/csv-response-classes/index.ts
@@ -0,0 +1,4 @@
+export { SingleAnswerResponse } from './SingleAnswerResponse.class'
+export { ArrayAnswerResponse } from './ArrayAnswerResponse.class'
+export { TableResponse } from './TableResponse.class'
+export { Response } from './Response.class'
diff --git a/src/public/modules/forms/helpers/response-factory.js b/src/public/modules/forms/helpers/response-factory.js
deleted file mode 100644
index e78ad6e820..0000000000
--- a/src/public/modules/forms/helpers/response-factory.js
+++ /dev/null
@@ -1,18 +0,0 @@
-const {
-  SingleAnswerResponse,
-  ArrayAnswerResponse,
-  TableResponse,
-} = require('./csv-response-classes')
-
-const getResponseInstance = (fieldRecordData) => {
-  switch (fieldRecordData.fieldType) {
-    case 'table':
-      return new TableResponse(fieldRecordData)
-    case 'checkbox':
-      return new ArrayAnswerResponse(fieldRecordData)
-    default:
-      return new SingleAnswerResponse(fieldRecordData)
-  }
-}
-
-module.exports = { getResponseInstance }
diff --git a/src/public/modules/forms/helpers/response-factory.ts b/src/public/modules/forms/helpers/response-factory.ts
new file mode 100644
index 0000000000..3266101d50
--- /dev/null
+++ b/src/public/modules/forms/helpers/response-factory.ts
@@ -0,0 +1,78 @@
+import { hasProp } from '../../../../shared/util/has-prop'
+import { BasicField } from '../../../../types/field'
+import {
+  ArrayResponse,
+  DisplayedResponseWithoutAnswer,
+  NestedResponse,
+  SingleResponse,
+} from '../../../../types/response'
+
+import {
+  ArrayAnswerResponse,
+  Response,
+  SingleAnswerResponse,
+  TableResponse,
+} from './csv-response-classes'
+
+/**
+ * Converts a field record into a custom response instance
+ * @param fieldRecordData Field record
+ * @returns Response instance
+ * @throws Error when data does not fit any known response type
+ */
+export const getResponseInstance = (
+  fieldRecordData: DisplayedResponseWithoutAnswer,
+): Response => {
+  if (
+    isNestedResponse(fieldRecordData) &&
+    fieldRecordData.fieldType === BasicField.Table
+  ) {
+    return new TableResponse(fieldRecordData)
+  } else if (
+    isArrayResponse(fieldRecordData) &&
+    fieldRecordData.fieldType === BasicField.Checkbox
+  ) {
+    return new ArrayAnswerResponse(fieldRecordData)
+  } else if (isSingleResponse(fieldRecordData)) {
+    return new SingleAnswerResponse(fieldRecordData)
+  } else {
+    // eslint-disable-next-line typesafe/no-throw-sync-func
+    throw new Error('Response did not match any known type')
+  }
+}
+
+const isNestedResponse = (
+  response: DisplayedResponseWithoutAnswer,
+): response is NestedResponse => {
+  return (
+    hasAnswerArray(response) &&
+    response.answerArray.every(
+      (arr) =>
+        Array.isArray(arr) &&
+        arr.every((value: unknown) => typeof value === 'string'),
+    )
+  )
+}
+
+const isArrayResponse = (
+  response: DisplayedResponseWithoutAnswer,
+): response is ArrayResponse => {
+  return (
+    hasAnswerArray(response) &&
+    response.answerArray.every((value) => typeof value === 'string')
+  )
+}
+
+const isSingleResponse = (
+  response: DisplayedResponseWithoutAnswer,
+): response is SingleResponse => {
+  return hasProp(response, 'answer') && typeof response.answer === 'string'
+}
+
+type AnswerArrayObject = {
+  answerArray: Array<unknown>
+}
+
+const hasAnswerArray = (response: unknown): response is AnswerArrayObject => {
+  return hasProp(response, 'answerArray') && Array.isArray(response.answerArray)
+}
diff --git a/src/public/modules/forms/services/submissions.client.factory.js b/src/public/modules/forms/services/submissions.client.factory.js
index d0551a0a97..d04fae5570 100644
--- a/src/public/modules/forms/services/submissions.client.factory.js
+++ b/src/public/modules/forms/services/submissions.client.factory.js
@@ -1,6 +1,8 @@
 'use strict'
 
-const CsvMHGenerator = require('../helpers/CsvMergedHeadersGenerator')
+const {
+  CsvMergedHeadersGenerator,
+} = require('../helpers/CsvMergedHeadersGenerator')
 const DecryptionWorker = require('../helpers/decryption.worker.js')
 const { fixParamsToUrl, triggerFileDownload } = require('../helpers/util')
 const { ndjsonStream } = require('../helpers/ndjsonStream')
@@ -96,7 +98,7 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
             }
 
             let resUrl = generateDownloadUrl(params, downloadAttachments)
-            let experimentalCsvGenerator = new CsvMHGenerator(
+            let csvGenerator = new CsvMergedHeadersGenerator(
               expectedNumResponses,
               NUM_OF_METADATA_ROWS,
             )
@@ -136,8 +138,13 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
                 }
 
                 if (csvRecord.submissionData) {
-                  // accumulate dataset if it exists, since we may have status columns available
-                  experimentalCsvGenerator.addRecord(csvRecord.submissionData)
+                  try {
+                    // accumulate dataset if it exists, since we may have status columns available
+                    csvGenerator.addRecord(csvRecord.submissionData)
+                  } catch (error) {
+                    errorCount++
+                    console.error('Error in getResponseInstance', error)
+                  }
                 }
 
                 if (downloadAttachments && csvRecord.downloadBlob) {
@@ -230,7 +237,7 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
                         GTag.partialDecryptionFailure(
                           params,
                           numWorkers,
-                          experimentalCsvGenerator.length(),
+                          csvGenerator.length(),
                           errorCount,
                           attachmentErrorCount,
                           timeDifference,
@@ -240,7 +247,7 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
                           new Error(
                             JSON.stringify({
                               expectedCount: expectedNumResponses,
-                              successCount: experimentalCsvGenerator.length(),
+                              successCount: csvGenerator.length(),
                               errorCount,
                               unverifiedCount,
                             }),
@@ -248,18 +255,16 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
                         )
                       } else if (
                         // All results have been decrypted
-                        experimentalCsvGenerator.length() +
-                          errorCount +
-                          unverifiedCount >=
+                        csvGenerator.length() + errorCount + unverifiedCount >=
                         expectedNumResponses
                       ) {
                         killWorkers(workerPool)
                         // Generate first three rows of meta-data before download
-                        experimentalCsvGenerator.addMetaDataFromSubmission(
+                        csvGenerator.addMetaDataFromSubmission(
                           errorCount,
                           unverifiedCount,
                         )
-                        experimentalCsvGenerator.downloadCsv(
+                        csvGenerator.downloadCsv(
                           `${params.formTitle}-${params.formId}.csv`,
                         )
 
@@ -271,18 +276,18 @@ function SubmissionsFactory($q, $timeout, $window, GTag) {
                         GTag.downloadResponseSuccess(
                           params,
                           numWorkers,
-                          experimentalCsvGenerator.length(),
+                          csvGenerator.length(),
                           timeDifference,
                         )
 
                         resolve({
                           expectedCount: expectedNumResponses,
-                          successCount: experimentalCsvGenerator.length(),
+                          successCount: csvGenerator.length(),
                           errorCount,
                           unverifiedCount,
                         })
                         // Kill class instance and reclaim the memory.
-                        experimentalCsvGenerator = null
+                        csvGenerator = null
                       } else {
                         $timeout(checkComplete, 100)
                       }
diff --git a/src/app/utils/has-prop.ts b/src/shared/util/has-prop.ts
similarity index 100%
rename from src/app/utils/has-prop.ts
rename to src/shared/util/has-prop.ts
diff --git a/src/types/response/index.ts b/src/types/response/index.ts
index 06c9e6ceb6..a9b75836d1 100644
--- a/src/types/response/index.ts
+++ b/src/types/response/index.ts
@@ -56,3 +56,21 @@ export interface IClientEncryptSubmission extends IClientSubmission {
   encryptedContent: string
   version: number
 }
+
+export type DisplayedResponseWithoutAnswer = {
+  _id: string
+  question: string
+  fieldType: string
+  isHeader?: boolean
+}
+
+export type ArrayResponse = DisplayedResponseWithoutAnswer & {
+  answerArray: string[]
+}
+
+export type NestedResponse = DisplayedResponseWithoutAnswer & {
+  answerArray: string[][]
+}
+export type SingleResponse = DisplayedResponseWithoutAnswer & {
+  answer: string
+}
diff --git a/tests/unit/frontend/forms/helpers/CsvMergedHeadersGenerator.test.js b/tests/unit/frontend/forms/helpers/CsvMergedHeadersGenerator.test.js
index ab72ebb532..11c0564a72 100644
--- a/tests/unit/frontend/forms/helpers/CsvMergedHeadersGenerator.test.js
+++ b/tests/unit/frontend/forms/helpers/CsvMergedHeadersGenerator.test.js
@@ -1,7 +1,7 @@
 import { stringify } from 'csv-string'
 import moment from 'moment-timezone'
-
-import CsvMergedHeadersGenerator from '../../../../../src/public/modules/forms/helpers/CsvMergedHeadersGenerator'
+import { getResponseInstance } from '../../../../../src/public/modules/forms/helpers/response-factory'
+import { CsvMergedHeadersGenerator } from '../../../../../src/public/modules/forms/helpers/CsvMergedHeadersGenerator'
 
 const UTF8_BYTE_ORDER_MARK = '\uFEFF'
 const BOM_LENGTH = 1
@@ -33,9 +33,20 @@ const generateHeaderRow = (append) => {
     question: `mockQuestion${append}`,
     fieldType: `mockFieldType${append}`,
     isHeader: true,
+    answer: '',
+  }
+}
+
+const generateEmptyRecord = (append) => {
+  return {
+    _id: `mock${append}`,
+    question: `mockQuestion${append}`,
+    fieldType: `mockFieldType${append}`,
   }
 }
 
+const expectedErrorMessage = 'Response did not match any known type'
+
 /**
  * Reshapes a mock record to match the expected shape in generator.unprocessed.
  * @param {Object} mockRecord
@@ -46,7 +57,7 @@ const generateHeaderRow = (append) => {
 const generateExpectedUnprocessed = (mockRecord) => {
   const reshapedRecord = {}
   mockRecord.record.forEach((fieldRecord) => {
-    reshapedRecord[fieldRecord._id] = { _data: fieldRecord }
+    reshapedRecord[fieldRecord._id] = getResponseInstance(fieldRecord)
   })
   return {
     created: mockRecord.created,
@@ -238,6 +249,79 @@ describe('CsvMergedHeadersGenerator', () => {
         expectedQuestionHeader,
       )
     })
+
+    it('should reject response without answer and answerArray', () => {
+      // Arrange
+      const mockDecryptedRecord = [generateEmptyRecord(1)]
+      const mockRecord = {
+        record: mockDecryptedRecord,
+        created: mockCreatedEarly,
+        submissionId: 'mockSubmissionId',
+      }
+      expect(generator.unprocessed.length).toEqual(0)
+
+      // Act
+      const addRecord = () => generator.addRecord(mockRecord)
+
+      // Assert
+      // Check error
+      expect(addRecord).toThrow(Error)
+      expect(addRecord).toThrow(expectedErrorMessage)
+      // Record should not be added
+      expect(generator.unprocessed.length).toEqual(0)
+      // Check headers
+      expect(generator.fieldIdToQuestion.size).toEqual(0)
+    })
+
+    it('should reject response with non-string answer', () => {
+      // Arrange
+      const invalidResponse = generateEmptyRecord(1)
+      invalidResponse.answer = 1
+      const mockDecryptedRecord = [invalidResponse]
+      const mockRecord = {
+        record: mockDecryptedRecord,
+        created: mockCreatedEarly,
+        submissionId: 'mockSubmissionId',
+      }
+      expect(generator.unprocessed.length).toEqual(0)
+
+      // Act
+      const addRecord = () => generator.addRecord(mockRecord)
+
+      // Assert
+      // Check error
+      expect(addRecord).toThrow(Error)
+      expect(addRecord).toThrow(expectedErrorMessage)
+      // Record should not be added
+      expect(generator.unprocessed.length).toEqual(0)
+      // Check headers
+      expect(generator.fieldIdToQuestion.size).toEqual(0)
+    })
+
+    it('should reject response with non-string answerArray', () => {
+      // Arrange
+      const invalidResponse = generateEmptyRecord(1)
+      invalidResponse.answerArray = [1, 2, 3]
+      const mockDecryptedRecord = [invalidResponse]
+      const mockRecord = {
+        record: mockDecryptedRecord,
+        created: mockCreatedEarly,
+        submissionId: 'mockSubmissionId',
+      }
+      expect(generator.unprocessed.length).toEqual(0)
+
+      // Act
+      const addRecord = () => generator.addRecord(mockRecord)
+
+      // Assert
+      // Check error
+      expect(addRecord).toThrow(Error)
+      expect(addRecord).toThrow(expectedErrorMessage)
+      // Record should not be added
+      expect(generator.unprocessed.length).toEqual(0)
+      // Check headers
+      expect(generator.fieldIdToQuestion.size).toEqual(0)
+    })
   })
 
   describe('process()', () => {