As soon as I started reading, listening to the Herald, I was totally immersed in the world you describe! Very powerful and cinematic music sustaining the story. Very good start!
Good sound design here and there to support the whole thing help in that sense too. I liked The Forest spirits, there are some very good and pleasant composition ideas in it :)
Beautiful chords in Seaside respite, calming after the encounter of the previous track.
Gluttonous miasma had the same effect on me the beginning did. More powerful, immersion I guess, I want to read a book of yours with the music accompanying it!
The last track was maybe too much different and I lost a bit of that perfect immersion, still is was a good ending reflecting the star theme.
Overall I think you have really strong abilities in telling stories musically, it felt like a real trip! Be careful with overcharging track as said below, it wasn't that annoying, but I imagine listening to the same OST with more space and man, that would be a blast by reinforcing your strengths at setting a scene!
Very good job and thank you for making me have this experience :)