Clean up i18n translations

[zachgoll]

My original reason for opening this was to fix the following error when running i18n-tasks add-missing:

(base) maybe $ i18n-tasks add-missing
/Users/zachgoll/.rbenv/versions/3.3.0/lib/ruby/gems/3.3.0/gems/i18n-1.14.4/lib/i18n/backend/base.rb:65:in `translate': reserved key :default used in "Value. Interpolates: %{value}, %{human_key}, %{key}, %{default}, %{value_or_human_key}, %{value_or_default_or_human_key}" (I18n::ReservedInterpolationKey)

          raise ReservedInterpolationKey.new($1.to_sym, entry)

It looks like this is an upstream issue as pointed out here.

Given it's not critical to the project, I decided against any temporary workarounds. Instead, we'll just manually fill in translations until the upstream fix is implemented.