There was a point in time where Sakurai stated how difficult it was working with third-parties to get characters in Smash. Just third-parties in general, not of any specific region. The statement would regularly get bandied about, and this curbed expectation as to how many we'd receive, thinking it'd number no more than two or three a game.
And for a while we were right, and then we were wrong. And then we were spectacularly wrong.
I've no doubt it's difficult to negotiate with third-parties, and I've no doubt the language barrier adds even more difficulties to an already strenuous task. But no one remembers the original quote of Sakurai speaking on how hard it will be to add third-parties in general to Smash, and even if they do it no longer affects their expectations. Eventually, perhaps not with this game, but eventually, people will no longer factor in the one specifically talking about western third-parties either.