And the other planes, like Phyrexia (basically "land of Phyresis") seem to have etymologies for their names...
So, what's the etymology of the name Eldraine?
This is speculation without WotC citation, but my guess would be:
First part coming from eldritch, it's own etymology described here.
Less certain about the second part (maybe it just sounded good), but in both English and French the suffix -aine means "approximately".