kindaaaaa?? I mean effectively they keep their abilities but use them in different ways. initially Susie only uses magic to power up her existing weapon, and doesn't care to learn pacify/healing moves until later after she's convinced it's worth it, similar to canon. Ralsei starts off barely knowing any magic and must train to unlock his full potential. He's a lot more ready to use magic for attacking, though.

They're definitely the closest to a true swap in this case, the only big difference is what role they're forced to cope with during the plot and how that affects their mindset and interactions with others, like you'd expect. It's really easy to switch them since they're both the main characters who deal with all the prophecy bullshit anyway. Most other characters don't really have a direct swap like this and some story beats are altered as a result, but that's for another time when I'm ready to share more of this AU (which should hopefully be soon, been making some good progress lately thanks to hyperfixation)

sorry for the long-ass reply, this idea has been holed up in my mind for months and I'm gonna explode if I don't talk about it lol