Also, I really don't think Corybantes are what you're looking for, at least not if they're to have any resemblance at all to their mythological forms. They really aren't little cupids who'd be likely to do a mortal's bidding -- they're divine beings in their own right who attend upon
Incidentally, Elves (Elfi) are well known in Italy, whereas Nymphs are practically unknown in popular superstition. People must understand that Italy is not ancient Rome, much less ancient Greece! A great deal of Italian folklore is of Teutonic descent, although that should not be taken as a rule. Mainly, because of the whirlpool of different traditions that Italian culture history has been, you end up with quite original and very local matters. But a "house-elf" - elfo domestico - is perfectly appropriate, especially since domestico is a frequent expression for a house servant.