Depending on the game, there's a decent chance someone will make an mtl within a few months if you don't mind waiting. Otherwise, if you want to translate yourself, you'll probably have to translate line by line. Common combo is Textractor + DeepL, it's a little messy but it works. If you want to translate in bulk, I think it involves automating the process where you copy line -> send to mtl -> receive input and paste to text file editor -> repeat for next line until the entire file is done. But you should ask someone else about that, I don't do bulk mtl.