Sylph was created in the likeness of an Astral's dead wife. Otherwise, Astral lore is still fairly undercook in the game. Skyfarers have gotten the lion share of development, Primal Beasts after that, and Astrals in a distant 3rd. We still don't know the identity of the Astral god.
They're also prepping the introduction of the Lunarians in the next couple years, possibly much sooner.
