Literally it means "sky child"
And thats the only piece of "controversy" i was able to find. Some believe they are meteorites, some believe they?re growing wild or can be cultivated
Some Schoolars beleive that the Ayleids had found a way to Cultivate the Welkynd stones, growing them like the Telvanni of Morrowind grow their towers. This argument is surpoted by the Ayleid's use of Welkynd magic, suggesting the stones are processed through this magic which shapes and forms the Stones. Also there is the schoolar, Lithnilian, who claims to have found a cave containg Welkynd stones, which may be either wild or cultivated. There is little evidence to suggest that the cave he found is a Cultivate collection of stones. If indeed it is a wild cave then it no doubtly puts the theory of "meteoric glass" out of the question, but if it is indeed a cultivated collection of stones then it proves the Ayleids were far beyond us in this area of magic as no mage today has been able to grow, produce or even restore a used stone