You can search in DF while manually choosing JP GE FR and EN when you register regardless of your character's locale or setting.

I can queue up as GE even though my regional settings set to EN and play in Deutschland. If you tick all 4 of them, I think you going to have to wait til someone else DF's with all 4 of them ticked. Just choose one, and EN is the most popular one.

Ich hoffe das hilft.