The original Japanese title only says "become a long ear" and uses "long ear" as some kind of slang term for "elf". Whoever translated the tile probably thought "long ear" alone sounds weird and added "elf" to clarify.
That said, elves don't always have long ears. They have pointy ears, but there are various settings with short pointy ears, like in the LOTR movies (not sure how it's described in the books).