What you're experiencing Martin, is rare.
That's all I can say from my own collection that just about now, covers all types of films from the oldest acetate b/w prints on Super 8 to 200, 400 ft shorts and digests from the 70's through to the most troublesome of lumpy pasted striped films from the later years.
Storage methods, location and conditions do play their part as of course does common sense, projector health and owner activities using said projectors!
Any stripe could and can very very easily, become ruined forever in the wrong hands just as the transparencies also could and can.
For the most part though, thankfully these type of ill treatments and bad practices are at least fairly uncommon and in the right hands, stripe should remain decent if it was even half decent in the first instance, using all good procedures and practices.
I've never known FG damage any kind of stripe but I agree, apply too heavily and it will affect immediately played back sound and it will also not allow the best recordings to be made.
If over applied better to remove some with a dry cloth or allow to dry out for a time before recording a film or screening one.