I think the idea of "super groups" is a good idea, perhaps with multilingual titles. There are probably lots of groups with similar subject matter that are separate groups only because the owners speak different languages; for example, I belong to "Church" groups in three different languages. Having a "super group" or multilingual group tag would allow people to explore similar groups that they wouldn't otherwise think of looking at because of language differences. I think the individual groups should however continue to exist, because I think people should only join a group if they understand the language the rules are written in (yes, I know I'm in a couple of Bulgarian groups, but that's because somebody invited me!).
However, since the beginning of groups there has not so far been much official response to suggested enhancements (like making it easier for a moderator to remove an offending picture without having to scroll through hundreds of pages to get there!); so we shouldn't hold our breath...