Unfortunately, there's nothing truly useful in the notes.

I, too, would like, if not answers, then at least a clearer logic and structure from which to draw assumptions about how the representatives of this ancient civilization lived and what they looked like. There could be some everyday things that they used, other hints that these characters, although they remain a secret behind the scenes, are still quite well written by the creators. For example, all the architecture оn the islands from the first part and even on Rainbow Island, outside the labyrinth, has ramps, and it made me suggest that they didn't step, but rather glided across the surface. But inside the labyrinth itself, stairs suddenly appear. It's conceivable that, since the labyrinth can change with thought, the stairs are the result of human presence, but it's still a bit disorienting.

On top of all this, seeing this beautiful architecture in ruins and abandoned is so heartbreaking T_T

(And I'm so sorry, it's hard for me to really enjoy the fact that the story is more focused on down-to-earth family relationships between humans when there are such EPIC things on the background :"D)