Did a quick test, Allies setting all aircraft to Interdiction on T1 and Axis moving their available units around at full speed, no significant combats.
Looking at the 2006 version of this scenario, two things stand out in regard to air-ground interaction.
1. The Allies have a lot of aircraft, over 600 I estimate, that fly in groups of sixty. That is a lot of firepower.
2. The order of battle depicts the Germans at battalion and company level. German AA battalions are shown as integral units and seem to have no assets distributed among the tank battalions etc. This means that when a German non-AA unit moves and is subjected to an interdiction strike, it is using the AA power that comes from machine guns, etc. -- not much to strike back with.
Been a long time since I read much about that campaign, but I don't recall the Germans being subjected to air strikes all over the place ... perhaps someone here has better recall on that point.
So: On the face of it, Allied air seems too strong considering game mechanics and the distribution of German AA equipment.
Easy to write about, less easy to fix. Options might be to lessen the numbers of Allied aircraft, or modifying the equipment characteristics of the aircraft in the scenario to have a weaker 'bite'.
Cheers