The problem is not the airfoil shape -it is the strength of the scaled down shape
H9 does a flat bottemed setup because it's easy to do and is thicker than the original full scale shape.
Th thicker shape is more rigid
The tiny EFlight curved foam setups are curved to again provide strength at lowest possible weight - that and thread rigging. (I have had em and they work well but you have to get em rigged correctly).
Airfoils are ALL simply compromises for the speed and load on the airframe
No exceptions.