OST tracks not heard in the game?

Hi everybody!

I was wondering about something that has boggled me for a while: I’ve been playing Sunless Sea for quite a while now but some of the music tracks from the OST have never popped up anywhere yet. I was wondering if they were played somewhere in the game or if they were specifically made for the OST. Those tracks are Dark Sailing, Harmonium over Matter, Hull is other People and Vox Zombius. Have somebody heard them?

Thank you :)

Iirc one of those is only played for some variants of the empty tiles and another is only played while above 90 Terror.