Looking at a cutaway drawing of the Flanker in "International AIR POWER Review" vol 8, the wing outboard of the flaperons is fixed, not a movable surface. There's no hinge line visible for that part of the wing in the photos.. ( Lots of neat color schemes on that one!)
Flaperons per se are generally used on gliders, where camber changing is used for different flight configurations.
For a jet model, they'd probably be overkill.
Flaps alone might be OK, if tailerons are used for lateral control, otherwise flaperons would make sense on a jet, but on the Su the span of the aileron is less than the span of the horizontal, which would have more authority in roll.
The dual-slotted flaps would be a mechanical problem on a model, and another problem to make the back part into flapeons.
Best to use them as single flaps (erons)..
I note the Su-27KUB (carrier version) does have movable outboard surfaces, probably added to assist the approach speed to the carrier.