Ancient Cistern:
Reminds me of an old SNES RPG game. There's a lot of good melodic ideas throughout! I have a couple things that I could recommend that would enhance the song. First of all, having an 'implied' bass note on one note for the entirety of the song sort of drags out the repetitive nature. In order to fix this, you can have a dedicated bass pattern that provides the chord progressions, because right now, it feels every interpretive where the chords are. Second of all, having a soft lush pad in the background will fill up that emptiness. You can keep some areas empty because of the water dungeon feel, but the whole song shouldn't feel entirely empty.
Flood Keeper:
The implied chords are stronger in this song and I like that! From what I can hear, the boss is pretty large because of how slow the song feels. Perhaps the beginning drum notes are the Flood Keeper's steps. That's what I thought anyways. I like how the song picks up in speed later on, which gives the piece contrast. Again, the bass notes will drastically impact how we hear the melody we're trying to pick up on.
Thanks eternityKitten for your awesome submission!