I'm not in front of my computer (macOS).
What I would immediately try:
I'd make a copy of the engine_iae. I'd rename the copy as engine_cfm.
And I would copy the folder in ~/Appplication Support/Aerofly FS 4/Aircarfts/a320/engine_cfm
The files stored here take over the original ones in the installation folder (it's non destructive).
And I would try the A320 and listen to the sound.
If Aerofly crashes after that, you just have to delete the added folder engine_cfm
All the manipulations have to be done Aerofly application closed.