I've just installed Fedora 17 a couple days ago. I set language and region to be English for system and I occasionally set them to be Japanese for user.
Problem is that the keyboard mapping is changed to the one for Japanese but the language toggle key doesn't switch between the languages properly, it's always English mode. I tried to set the language and region to be Japanese for user. But the situation remains the same.
Before upgrading Fedora to version 17, I ran Fedora 15 in which this problem did not happen.