Vehicles, particularly the PnZ IV H, should be much, much tougher.
20mm cannons should only have a small, very small, chance of destroying the PnZ's engine or tracks.
PnZ's should be nigh immune to 20mm fire, let alone 12.7mm or 30 cal fire.
The RAF ordered the Mosquito FB.XVIII with the Mollins 57mm cannon as an anti-tank weapon, but by the time the FB.XVIII was ready they had concluded that the 57mm Mollins gun lacked sufficient penetration to destroy German tanks effectively and so gave the FB.XVIIIs to Coastal Command. That was a 57mm cannon that wasn't good enough, 989,000 joules at the muzzle. Hispano MkII 20mm cannon, by comparison, have a mere 50,300 joules at the muzzle.
There is no way that aircraft guns, not even the Yak-9T's 37mm or the Hurricane Mk IId's 40mm, should be anywhere near this effective agaist tanks. Bombs and rockets should be the only realistic hope a pilot has of doing anything to a tank, and the rocket needs to actually hit the tanks, the bomb needs to be damn close.
