I looked into this when I was trying to identify a kill claimed by an NSG 9 Fw 190 pilot, Werner Hensel. What I came up with was:
If it was an American aircraft then it must have been one of the three 416th NFS Mosquitoes that failed to return from a strafing mission in the dawn hours of the 22nd. Although these too are understood to have fallen to Flak and their patrol area was in Map Square F (which did not reach as far south east as Ferrara).
I also have a note of information from Alex Smart: "I have NF30's serial numbers MT482...416 NFS...MACR 14065...22/4/45 NT248...416 NFS...MACR 14064...22/4/45"
My original best guess was that it was an RAF Mosquito that Hensel had shot down (the circumstances matched fairly well) but later established that it was a P-61:
see this page.