I'd whant to see the Flaktrack, this unit need a little changes, but how you whant counter penals and guards spam with mortar HT ? or hit the planes ? OKW have ISG for inderect fire or zu fast.
I never had a problem with planes while not building FlakHT. And FlakHT horribly fails against blobs.
Since OKW have cheaper suppression unit know as infamous MG34, there is little to no reason to build FlakHT and it doesn't scale, it's a dead unit from the beginning.
ISG is weak and stuka don't give you constant pressure on the map and it's too expensive to counter t0 or cheaper tier in comparison to mechanized.
Planes can be killed with schwerer panzer HQ.