Hello.

This translations step 1 looks pretty good to me.
C++11 was the preferred choice, nice that it worked out.

Here are my usual nitpicks:
• The game should not crash when FontFileName cannot be loaded. Either remove the option or make it fallback to built-in font. Currently it locks out the game, that is unacceptable.
• Don’t use macros, they are only to be used as last resort.
• Language list in options should use human readable language names, as in v1. There should be no NUMBER in user language list.
• Do not use strings for language id, instead use enum directly. I would prefer if you used v1 language enum names, such as English vs en.
• I would like translation_id_e name shortened, to something like Msg or Ids.
• Forward declare translation stuff in the header. translated_strings should be private static?
• Check translations.h includes, some could be unused or provided by pch.

That is all for this review.
I am going to bring in more FT stuff; it should not conflict with your things.

About the macro, I think I can use InitializedArray to have the display name associated with the language enums.
To avoid the NUMBER item in enums, I can use a std::vector instead of a fixed array inside InitializedArray, I don't think there is a performance penalty, this will just do one more allocation.
But there won't be any compile time check of the array size then, so do you really think its better without NUMBER enums ? unless there is a way to handle that somehow

translated_strings is in an anonymous namespace, this is the same as static, but allowing a declaration so I can keep it's definition at the end of the file (as the definition is very long).

I believe there is a miscommunication happening here.
I will take a more hand on approach with my suggestions by applying them directly to add-translations2.

This PR is now aligned with my vision™))

One last thing for you to do before the merge:
Remove placeholder English texts from missing translations (for example in Menu1_UseMaxResolution_640x480).
This is misleading, makes it hard to see actual translation state of the game.
Translation array initialization should be sparce, with missing texts set to null by default.

Thanks for your changes, I've done the removal of English texts for non-English languages.

Alright, this PR is now good to go.
Thank you for taking this brave first step into the world of cross-platform localization support)

Up next - my plans for localization support v1:
• Embedded font - stripped pan-Unicode, spliced two fonts, something else.
• Auto system font support, per platform folders, known good font names, language specific fonts (CJK), font selection from list.
• ImGui font handling changes.