How do I change the language from the Russian version of 3.1 to English?

I think he probably figured it out. By the way, I would prefer to listen to clear English speech rather than quiet Russian. But you don't need a patch; you need the English voiceover itself. Unfortunately, I don't have the game, so I can't say for sure which folder's resources need to be replaced. In any case, you need to find someone with the English version to share the files with the original speech with you.