They might. In the Japanese version Simon's name is pronounced 'She-mon' because the katakana they used for Simon's name is 'シモン'.(Don't ask me why they spelled it like that. They can spell it サイモン, which is our way of pronouncing Simon. For some reason they decided to go with She-mon.) From the start it's totally different. However in Isaac's case they might reuse Robin's annoucer call since it's not totally different like Simon. I mean Japanese people know English, so they know Robin is Robin. If that applied to every characters, then someone like Marth would've had a different call between Japanese and English versions.
Exactly. You can take some liberties in translating Japanese (especially with likes L vs R, S vs TH, and V vs B, which are super common mistranslations), but Robin would actually be pronounced the same way. They might re-record it anyway, but if they didn't want to get another announcer call they could easily just re-use the English one. The Fire Emblem characters that have the same name in both languages are a good example of this: Marth, Roy, Ike, and Byleth all have the same name in Japanese and English, so they share an announcer call, despite the pronunciations technically being different (in fact, Byleth's male and female names are different, but they still use the same "Byleth" announcer call).
I don't see how the japanese name is an issue. In Japanese Robin's name is Reflet. So if you put the game in japense, you'll have Robin and Reflet, in english you get Isaac and Robin, in french you get Vlad and Daraen, in spanish you get Hans and Robin (I assume, dunno if Robin's name is different in spanish). I don't think you can change the announcer language individually.
I was more referring to discussion, especially between Japanese and English communities. When we talk about "Isaac", it's commonly assumed to be Isaac from Golden Sun, but if that discussion was translated into Japanese without the context, it could be referring to the Binding of Isaac or another game that I can't think of with Isaac as the protagonist, but
not Golden Sun, unless the translator took care to change Isaac to Robin. And vice versa, we already
have a character named Robin in Smash in English, so again translations would have to careful and aware of context.
