I have a decently leveled character that I leveled up on pc with. I just saw that I can finally download the US version on ps4 recently and when I got to the log in it asked me to register. I'd really rather NOT level up all the way to where I am again on pc if they're completely different servers or something then I guess I won't be playing.

I dont know where you got the idea that onigiri is cross platform. Or why didn't look a little bit more on the forum cause about 3000 people asked the same thing. Consoles only have content cap at echigo where pc has up to the moon. If it was cross platform it would be chaos with the lagg. So in short you can not log in with a pc account to ps4/xbox1 vice versa.