Hanezeve Caradhina is a song in the OST of Made in Abyss, composed by Kevin Penkin and sung by 斎藤洸 (Takeshi Saito).
Kevin Penkin, the composer, said this on what the lyrics meant:
It's not a real language, as we thought it would be better with this track to keep a certain amount of ambiguity in the vocals.
Regardless, in 2017 I decided to go and try to construct a “language” out of it, imagining what it could perhaps plausibly mean.