what about clutch protection on ME7? There is a map "Advance timing during gear shift"
but I am not sure if that retardation appears as CF!
If i disconect clutch switch manualy there is no change in high retard situation, i done that when i develop decision for that problem
On your situation may engine produce high noise when you add forged pistons so you have to calibrate optimal noise. That is quite hard procedure as you have to find where the engine make these noises and set the knock to hear there and tell to knock that these noises are not knocking.
We never use forged pistons on 1.8T engines except on stroker engines, we test stock pistons with stock CR with GT35 turbo on 2.4bar boost, 98RON fuel, and never had any problem with them, so piston swap is not the reason too, but anyway high retard problem after fast gearchange i get on almost every big turbo 1.8T, 2.8 V6 turbo or R32 Turbo car