This has a great deal of worldbuilding. The thing of it is it is hard to get drawn into it because the aliens are so alien. There needs to be at least a few points of similarity for people to be drawn into the story enough to care for the characters. There aren't really characters either. It reads like an encyclopedia entry rather than a story because of this. Stories need relatable characters for people to feel something. It aids understanding and enjoyment of a piece. There is also a lot of telling rather than showing. It sounds like this world is a very beautiful place but without a character describing how it feels to them it reads as flat.

I am not saying this is a bad piece. You have backstory, plot and conflict. You just need some identifiable characters to draw it all together. How do your aliens feel about the possibility of ceasing to exist? They need to be aware of it for them to feel fear anxiety or anything. The plot of this story seems to be the idea of a curious species wanting to leave a mark on a universe likely to move on without them because of the threat from a black hole. Own the plot! Make them struggle to survive, make them try to send messages to other worlds. Introduce the leaders, the followers, the adolescents so bothered by their phase of life that they may not choose to live. This could be a vibrant book!

The ideas you have are beautiful and unique. If this were me I would call this a good first draft or an excellent outline. The next step I would take is to choose some characters, flesh them out, make them alien, but also give them a little humanity so that readers can understand them. They need to have thoughts, feelings, gifts and weaknesses. It can be hard to create a well rounded character. Believe me I know, I still struggle with them with over 40 years of writing experience under my belt.

What you have going for you is what I struggled with for the longest time. A clear vision of what the story is about and where it needs to go. If you need help working up characters I have a questionnaire that I work with when I work mine up, a lot of the questions would probably not apply with your aliens but it should get you started understanding the kind of things you need to know to flesh them out.

This isn't a completed work of fiction but it is a good start. You have a story, a potentially really good one. I might suggest you reading Anne Mcaffery's crystal singer trilogy. It is about human characters in a crystaline environment and a highly alien intelligence is interacted with in the last book. The author really shows a good way of expressing these two things in a relatable way.

Another relatively minor issue that you really don't have to worry too much about at this stage is the fluid way you waver between tenses in your writing... From past to future to present tense wordings. I realize time on your planet is fluid but you need to write about it in a standardized way otherwise it can get confusing.

Thanks for letting me read this. I really enjoyed your creative ideas. If you need any help feel free to email me. I know getting started on a big project can be difficult, stressful and confusing.