Bugs aside, which I think should be fixed of course, the issue is not the effectiveness of the Stuka that you point to it is the AoE of the P47's. In order to prevent them from gibbing every infantry unit in the game when they miss their rockets have teenie tiny AoE. I agree with you that the P47 cost is unfair based on its current performance. I still don't think that means the Stuka should be altered, other than to address the alarming bug that allows it to loiter for much, much longer than it should.
stuka CAS both hits and has a large AoE that will instagib any infantry near the tank. i think that the p47 is both UP (due to the rockets having a hard time hitting even VIs if they're parallel to the p47) and that the stuka is OP because it does so much damage. the Il-2 is also shit.