Why is there a constant need to over complicate everything?
A turn has no bearing on flap extension or retraction.
Speed and the relationship to angle of attack and minimum speeds, of course, is very relevant. If you are too slow to retract flaps in the turn, then you are too slow. Period. Either speed up or wait. If you have adequate energy, margin, and speed, extend or retract in the turn.
Flap assymetry is flap assymetry, whether in the turn or not.
The aircraft doesn't know if it's in a turn or how high it is; flaps extended or retracted in a turn or 3 feet above the ground ..... it doesn't know or care where or when. It can't think, it can't see and last it knew, it was perfectly happy and content two seconds before you flew it into the side of a mountain.
Raising or extending flaps is perfectly safe in a turn, if you do it properly. Raising the flaps at 5 feet above the ground is perfectly safe, if done properly.
It should be done sensibly, just like anything else in an aircraft.
Your welcome...