Art: The paintings are great, but the graphic design isn't up to the same standards.
Writing: I appreciate the ambition here, especially given the jam theme. Some of the visuals are very evocative. I feel like there's a mismatch in scale between something this epic and the trifold format, however. A trifold adventure will necessarily be short and I think it's inevitable that the pacing will be off for a discovery on this scale. Perhaps a setting guide rather than an adventure would have been the way to go.
There's also a plot hole in terms of the atmospheric physics. Does the moon have enough gravity to sustain one or not? If not, then how is melting the ice caps going to make one? If so, then why is the interior going to explosively decompress if the crust cracks?
Game Design: The plot is gated at two key locations by puzzles that the players may not have a realistic in-character way to solve. How are they supposed to guess that the funicular is powered by blood? If no one has the requisite skills to know what the transit system is and how to activate it, then the endgame is only going to be triggered by players doing stuff "because it's there and the game designer obviously expects me to do something with it," which isn't particularly satisfying as a player.
Theme: Full marks. It's maybe more mythology than Mothership, and I would say maybe this leans too hard into science fantasy to work in a normal Mothership campaign, but I'm not going to penalize you for emphasizing the theme we were told to use.
Layout: The map is probably the weakest part of the visual design. The connections between the locations need a little more emphasis and in particular, I would give some space between the connections to/from the Temple and the painting, because they're almost invisible where they run alongside the edge of the art.
Utility: As written, I don't think the scope of the adventure matches the promise of the setup, so it would be hard to run a satisfying scenario just using what's in the pamphlet. From the player's perspective, they've discovered an entire moon-sized underground world full of giants to explore, and there would be an overwhelming amount of ad-libbing needed for the Warden to live up to that promise. Just ushering the players through two puzzle gates while rolling randomly for falling rocks would not be satisfying.
Favorability: TL;DR I love the concept, but not the actual adventure.