I just had a listen. I believe OpenMPT is unable to correctly/accurately handle any of the pitch glides (aka "pitch bends" in MIDI parlance) of that horn part in the MIDI, so such notes never reach their intended final pitches in the MOD.
Everything else seems to be converted okay.
I listened to the MIDI version and to be fair, the pitch glide effects are IMHO mediocre at best even in the original MIDI. While I'm not sure I have the time to do so, I'm thinking if I just edit the MIDI and just get rid of those mediocre pitch glides in that horn part, that would at least allow the OpenMPT conversion to not botch those notes.
There's always the idea of trying a different conversion program of course, though I have no experience with this and can't recommend anything myself.