I don't know anything about the comma in English in this case, but I am aware of the fact that in other languages there are more adequate equivalents for "hanem" - e.g. "sondern" in German or "sino" in Spanish.
"the apple is not Hungarian rather Dutch or Belgian" is another good answer, IMO
and by the way there is NO COMMA in English before BUT -- just in Hungarian
Actually the comma is fine in English, though it is optional.
I dont think this is a sentence that will every come up naturally in a conversation
Did you know that dutch and belgin are not the same?
The 'alma' and 'holland' buttons are lacking, wtf!
The 'belga' button is missing...??
That's because it said, "Pardon, ik ben een appel".