Wrecking a PZ4 with a Jackson with max range shots on the move isn’t balance, it’s garbage. At max range TDs/AT guns should’t have as much accuracy vs mediums, thus it would require you to either get a lot of shots in quickly, vet up your units or get closer, which would get rid of the current stagnant TD meta.
What are you talking about?
If target moves or not doesn't impact accuracy, unless you have activated blitz or combat blitz, which decrease temporarily target size.
If Jackson MOVES, agains P4 at 60 range it has whooping 38% to hit.
Moving SU-85 has 44% to hit.
Moving FF has 48%.
I wouldn't call it exceptionally high.