Hi! Deluded’s text is stored inside Unreal Engine .pak files, not normal text files. In the game folder, look in:
SRTE\Content\Paks\
The easiest way to inspect dialogue is with the free tool FModel. Open that folder in FModel and search for DI_, character names, quest names, or dialogue phrases.
Editing translations back into the game is harder because the files are cooked Unreal assets, so it would need proper modding/repacking tools, try using RePak.
For a public translation, it would be best to ask SRT first. Your Czech/English/Russian translation help could definitely be useful if they ever add official localization.