Looking up the various Hedge Traditions, Tempestrii led me to https://en.wikipedia.org/wiki/Magonia_(mythology)
It doesn't see to be mentioned in Lion and Lily, though I don't have a copy of Faith and Flame.
But still, a cloud realm whence felonious aerial sailors were said to have come according to Frankish belief in the 9th century. Has anyone played with sky pirates?
Presumably Faerie, but could be Magic realm.
There are the (HoH:S p.109) Tempestariae: classical weather-witches, that could crop up everywhere.
And there are the Cloudlands - Aiolia - by Ben McFarland in sub rosa #19, with a population of giants.
I had the remains of a Diedne covenant located in a regio above Lyon for an apprentices saga I ran many years ago. They had magical grogs that still lived there and sailed flying ships, but who were careful to avoid notice by the Order. They would fly over wagons from within clouds and shoot at them.
The Atlanteans were said to have sky structures, as I distantly recall. Or I may have made that up for the podcast.
I have found surprisingly little information on Atlanteans, other than the mechanical stats for making one descended from them.
They may have made Ladon / the spirit Draco.
Look up Gervaise of Tilbury and his Otia Imperialis - it mentions sky ships over England in the 13th century.