Probably not.
Adele belongs to
ADELHEID and has a completely different root. I don't know about
EIDEL. I don't see a connection between "eitel" (conceited, vain, mere) and "delicate": My Yiddish dictionary has "ejdl" for "fine, tender, delicate", but I can't find a
German equivalent even in Grimm's "Deutsches Wörterbuch".
Andy ;—)