The developer said something about adding translation support in the latest update. Not too sure how you could do this but I assume you have to manually translate things yourself.
There is a more detailed explanation in the game description on itch, but in short, to make a translation you find the en.lang file that auto generates inside "%localappdata%/gain_factory_reloaded_/language/active" and use it as a template to make the translation from. There is cyrillic support.
