The engine will use multiple translation files no problem, but you still need to use unique keys across all the files which is not ideal. So maybe there's a way to tell the engine which file actually use to find translation for specified key? For example if I have separate file for each NPC dialogue:
Bob.csv:
TEXT01
TEXT02
TEXT03
Jim.csv:
TEXT01
TEXT02
TEXT03
The engine will always use Bob.csv translations. And I'd want to tell the engine "use Jim.csv translations instead"