The model is suffering from low power -(low speed ) which produces (of course) -higher angle of attack .
the proper differential can be established for only ONE speed range - and if the wings are rigged correctly -this will be more UP than Down aileron travel
On an aerobatic bipe 4 ailerons - the best rigging is wings and ailerons -0-0
All of the early aircraft suffered from the same problems - too heavy and underpowered -which equalled - high AOA to get enough lift. (and more resultant drag.)
The H9 model will essentially need similar rigging . Be sure to NOT rig one wing at a different angle than the other - for best results.