As far as I remember, NA costumes can trade now, as long as it's permanent. I remember reading something like that when I tried it out and only played till lvl 25 lol.
Only the Rare costume pieces (not weapon costumes) can be traded. The only way to get the Rare costume pieces is to combine costumes using the Synthesis tablets and get lucky for it to become a Rare one. All other costumes are not tradeable including Wings and other things, and none of them can be stored in the Warehouse (sharing between characters on same account is impossible). NA hasn't changed much at all in that regard..!