I was thrilled when you said this was your adventure as I had it open to print already and is one of the ones I am most excited about reading. The Cube is one of my favorite horror films and this reminds me a of that a lot.
I love the interactive map and it's very clear how to assemble and operate it from a gameplay perspective. Any group would be thrilled for their GM to bust out a Rubix cube with this on it at the start of a session.
I love that you included drawings of Haumea and Kaulu, I think they add a lot.
Maybe bold phylactery in room 10 just to make it a bit clearer.
I like the Ohe Hano Ihu, the placement of it's details on the cover is a little odd, but I understand you have to make things fit where there is space. I wish it was integrated into the story a little bit more, maybe as part of the timeline it could included like, "Used her Ohe Hano Ihu to secretly casts a spell to grant Kaulu eternal youth."?
On a similar note, it might be fun to have the tortured remains of Kaulu's killer in one of the rooms.
This is minor, but I feel like you might want to rethink the font choice, formatting and background on pages 3 and 4. I'm not knowledgeable enough to make suggestions, but it doesn't feel like it all works together. For example, I thought the Mutants of Catfish Hollow and The Piteous Priests did a great job on their text heavy, white background pages of creating a cohesive and visually interesting vibe.
Excellent use of the theme, brilliant job with the map. This is a great dungeon crawl, very Appx. N. appropriate, supported by a really clever story device. Great job!
P.S. I just printed this out and ordered a Rubix cube, haha.