Avatar is the only PbtA system I've ever read (and never played or GMed any), but do systems have a significant amount of mechanics unique to each system, or is it all mostly flavour on top of the same system?
My initial reaction was confusion or intrigue, but the more I think about it, the more it makes sense.
I can definitely see that Avatar might be a system that makes sense for Star Wars. Combat is largely martial arts based, with magical ability to affect things at a distance. Plus non magic using characters (with weapons or technology) are important.
Narratively, the idea of balance is incredibly important in both worlds, and the balance mechanic is pretty core to the Avatar RPG. Three of the four core stats (focus, harmony, and passion) are super important in the existing Star Wars lore, and creativity is hardly a huge stretch to add.