I love
Elfriede! I've never heard of the nn Elfi for it before, but it makes perfect sense. And it's most cute. It's similar to another favorite of mine, Elvy / Elvie, from
Elva. There's an English actress named Elvi
Hale.
I don't think Elfi would work in an English speaking country because of the obvious word "elf." "You mean, like an elf?" would get really, really old. But I love that it is used in Norway.