Nothing like returning to your own thread 6 months after it died
I took a long break from SH4 but recently got the itch to give it another go. I downloaded your SH4 editor and had a look at those doppler values. Did the trick, I reversed the sign on all of the "air" sound entries, and now in the museum when you pan around the aircraft you get "correct" doppler effect (higher pitch when facing you, lower pitch when facing away). A quick test in the artillery training seemed to confirm that the behavior is fixed too.
Norman