I definitely think NA / EU / OCE. I would worry about both cultural differences with JP coming to other regions where we are, I guess, looser with things and gameplay differences causing conflict? We're not taught from a young age such strict social etiquette. I would not want that to turn into conflict and NA folks getting reported, for instance, for something that we're completely fine with.

There's also a concern about gameplay. From what I've seen, JP use DF and PF exactly opposite. Macros also seem to be fairly popular. Whereas macros in NA are usually just us being silly in chat. I could definitely see differences in opinion and arguments over those items.