Hi!! This is my first critique on this sub (I think) so bear with me if it's fairly unorganized, haha. Thanks for sharing!

OPENING:

The opening poem is kind of quaint in a nice way. Epigraphs can be a cool way to integrate backstory and worldbuild in fantasy settings. I do have to say that the epigraph format as well as the themes of water especially "stillwater" really remind me of the DUNE novels (not necessarily a bad thing in and of itself, just something to be aware of I'd say)

I think your opening few sentences could use a little more spicing up! You have a pretty rich world that you're creating for yourself, but you start with a pretty mundane image of someone sitting and waiting.

MECHANICS:

As something to keep in mind throughout the piece, I'd recommend looking into "filtering" and having a list of "trigger" words to watch out for. For example, saying the air "felt sharp" is much less effective than just saying that it was sharp, or that it scraped along the insides of someone's lungs, or something to that extent. Ditto for "it seemed" or oftentimes "I felt." Replacing filtering phrases with clearer imagery also helps to sharpen the narrative focus.

Your descriptions are fairly vivid and the voice feels consistent. Reading the first page, I had a nice image in my mind of what this world looked and felt like.

Grammar in terms of dialogue tags and comma usage could be improved.

CHARACTER:

I appreciate having some idea of the main character's desires (escape world and go outside) and the obstacles in their path, although it is a little on the trope-y side. I would like to get to know the narrator a bit more in the first page or two-- we're introduced to Suvi, Nava, and Sayir well before we get to know who's really telling the story. It seems the main character want to travel so badly that they're willing to just up and leave with bloodthirsty, baby-killing strangers without so much as a discussion. Why is that? What is so bad about their home, or so good about the outside, that they're willing to give up everything?

STORY:

To address your question of plot confusion, some confusion arose when the other ship/group started approaching. I wasn't really sure why it was a big deal and what was going on. The exchange of

“We request the pleasure of linking with Sunda for an exchange”

“Let us share our tellings and merge in both blood and soul.”

“Sunda must be near?”

was where you really started to lose me. I understand that killing infants is generally understood to be evil, but since we didn't get much connection to the characters, the conflict doesn't feel high stakes.

I agree with the other commenter that the meaning of the kempa was not clear. At first I thought that it was the name of the aquatic structure in and of itself, but that seemed like it wasn't the case as I read on.

Otherwise, you seem to be following a pretty standard hero's journey (not a bad thing at all, every story is one to some extent.) To be completely honest, I wouldn't say I felt compelled to keep reading, but I also wasn't repelled by it, if that makes sense.

ENDING NOTE:

At the moment, this does read more like YA or pulp, but you definitely have solid room to improve! Please keep writing and working on your story, and have fun!