That is part of it, they left the studio out for one.
None that won't be fixed with time, all it takes is someone ripping any translation out and somehow applying it to the Japanese version like the previous two games. With that said, I believe waiting for the Japanese version to get whatever benefits the Steam version has is the right call here.
None other than language and a lack of studio.
The translation is better if their previous Steam games are any indication, but that is not a benefit the Steam version will have to itself for long if STN has anything he can and wants to do about it.
It does not, STN hasn't had time to adapt the translation, but maybe in a version or two.