Some notes on air hitboxes that I've noticed.
Miyako's air hitbox is unusually low. F Kouma can actually 6c > 623b and land it, whereas it doesn't work against most others. Also, when doing F Miyako's corner combo against another Miyako, I have to add in an extra j.a or two in the air combo to confirm ex air elbow as the ender. Most people won't have a problem with this though.
Kouma's air hitbox is FUCKING WEIRD. I'm pretty sure it's just unusually high. It's definitely high enough that F Miyako cannot hit 2c on him while he's in the air, which means that even at the lowest possible height he has a gap between himself and the ground. Apparently his air hitbox fucks up all sorts of combos, so learn some alternative options against him.
Wara's air hitbox is massive (most charas won't have problems with combos vs Wara), but somehow still has the gap between him and the ground (like Kouma does), because F Miyako can't hit 2c on him while he's airborne either.
Aoko's air hitbox is like...really long vertically I think? I dunno how to explain it. Maybe she just has a low collision hitbox, or maybe it's really long. Whenever I get random ground-to-ground wallslam as Miyako, she is the only character that won't bounce over me.
Nobody else has any particularly weird quirks to note from Miyako's concern, other than standing hitbox stuff that's pretty obvious just by looking.