not much i have to say i think,
these are the hitbox names:
"small_hitbox_scale"
"smallcrouch_hitbox_scale"
"big_hitbox_scale"
"bigcrouch_hitbox_scale"
"fire_hitbox_scale"
"firecrouch_hitbox_scale"
(note: all crouch hitboxes have the small size!)
and you can have these sprites if you wanna:
SmallAHB.json
BigAHB.json
FireAHB.json