OK, thanks to someone who had used FMOD before, I think I found the problem.
The issue is indeed a libvorbis one.
The 3 files that fail are encoded with “Xiphophorus libVorbis I 20010225”, or “the vorbis codec from Feb 25, 2001”. All the other sounds (the ones that work) are encoded with the 1.0.1 codec.
So it means the newer codec doesn’t play oggs encoded with the old one.
When using the latest buildbot from today, in FMOD you get these errors because it probably uses the newer libvorbis.
But they play fine in OpenAL, which probably uses an older version. I think it means it won’t be able to play them too after it’s updated again. So I wouldn’t call it issue solved.
The best option I think would be to contact the libvorbis devs and tell them to support files encoded with the old encoder.
My only experience with libvorbis is Panda’s audio engine wrappers, so I don’t know if I could provide them with enough info.
Of course you can just try to re-encode them, but there’s no guarantee your audio program will use the right version and I can’t do that too because I can’t modify the game archives.