Yeah you take huge risks with vanilla Saints Row 2 as GotR fixes as well as alters many aspects of the game. Not to say GotR patched game is 100% problem free but it's a hell of a lot better than regular SR2 which is broken in many ways as you can tell.
As IdolNinja says about GotR: "The Gentlemen of the Row mod enhances the base game with additional content, and over 150 bugfixes and tweaks making Saints Row 2 a much more stable and rich experience. Some of the new content includes 100+ new clothing items with 120+ new logos, improved weather including a darker nighttime and more vibrant colors in daytime, plane and boat mechanics for customizing, additional missions, new vehicle dealerships, new weapons, new cribs, new homies and gang styles, more car paints, more skin colors, tattoos, makeup, optional 360/PS3 onscreen prompts, and even new cheat codes including NPC morphs (just to name a few.) All of these features have been extensively tested and confirmed to work correctly with either a new game and complete playthrough from start to finish, as well as being compatible with existing vanilla saves. Keep in mind certain new features aren't as slick as they could be. For example, the new vehicle stores have a naming problem when you buy them and it displays an strange name on the confirmation screen. Another example, is that Maero's monster truck can now be customized with everything except body paint. Doing so crashes the game, etc. I had to make a decision that the benefit of certain new features outweigh the problems with them.
While most of the Gentlemen of the Row mod is comprised of additions and enhancements, it also does permanently change some of the original features like certain taunts, compliments, walks, weapon meshes/skins, logos, and other things that may bother a purist."
I'm not sure what can be done. You could share some of your saves and see if others have the same issue maybe?
You 100% sure Steam Cloud is not restoring the changed language saved game?
Maybe do a search for Saints Row 2 save game crash and see what pops up.
Best of luck!