Main Theme: You do a great job in this piece keeping all the instruments moving, which feels like various breezes or gusts of wind blowing around at the same time. The cymbal crashes help give some heroism to the track making it feel right for a main theme.
A Journey in the Clouds: This is a light and airy theme which certainly adds to the main idea of ascending to the clouds. High strings and pizzicato style are nice for this type of sound.
Mia’s Theme: The flute and high strings with celeste work really nicely together. I also really like the chimes glimmering occasionally throughout.
Danger in the Wind: Having some lower register instruments adds some weight which makes the danger feel a little more in reach. I like the interplay between the strings and flute and then when they come together with the celeste it feels chaotic because of the rhythm, but organized because of the unison monophony.
Battle for the Crystal: The tension in the harmony helps this feel like a battle theme that would fit a game possibly similar to Pikmin in that maybe the battle isn’t super fast-paced, but there is constant danger present. I like the addition of brass instruments and bass drum to represent the evil creature.
Overall: Your compositional style lends itself really well to the story you have created. I like the combination of strings, flute, celeste, and percussion that isn’t too heavy. You are able to create a variety of emotions as demonstrated in each of your five tracks that feel like a complete story. Well done and thank you for sharing!