Better feedback when translation files have errors

[michaelbromley]

Is your feature request related to a problem? Please describe.
When a user supplies a translation file, and there are errors with the syntax, it will cause that translation to fail (only the tokens are displayed in the UI) without any clear error message. This has proven confusing to at least 2 users already.

Describe the solution you'd like
Investigate if there is some way to detect this and display a clear error message, ideally pointing out the part of the syntax which is wrong, if possible.