These tracks are good vibes! I love the 6/8 remix of the main theme as the menu theme-- these kinds of things are what give a soundtrack the cohesiveness they need to succeed.
The Earth track is a lovely change of pace, and I enjoy its playfulness and purity. The Voyage track is also really fun! Each track is joyful to listen to and reminds me of Undertale battle themes a lot. In each track, I would recommend adding more chord changes just to make things more interesting. The other changes you do have make for a couple of really interesting tracks! Synthpop for the win :)