FYI the reason why cross region doesn't involve Japan is because armor and weapons are different for the Japanese version. There are a lot of bonus collaborative equipment that got remodeled for the localized versions so the data is different.
This makes me very, very sad. But it would still be insane to spend another 250 on another WiiU, so I think I'll pass and remain happy with my 3DS-Version. All I wanted was to play with my European friends...