Flutter is caused by the ailerons CG being too far aft - it should be somewhere between the hinge line and 20% of chord
Good servos and tight linkages may overcome incorrect setups byt ther is no mystery about this and no fixes other than to get the balance located correctly.
IF the balance is wrong - a resonant swing can take place- sometimes quite easily and it is destructive
This is not just an "idea " It has been tested and shown to work.
also full scale practice is to balance ailerons .,This done not to change stick pressure but to prevent flutter.
Pulling out of a dive at speed - can reduce unequal pressures on wing/stab which at some point will allow the control surface (aileron or elevator) to "hunt" -at some point this can become a resonant swing -
play with hinge gap if you want to- that is just a patch and or acts as a movement restriction.