[stapled_socks]

The name in English seems a bit gimmicky. "Älv" in the context means "river" and not "elf". I guess someone choose to use this play on words in the translation to pique interest and garner sympathy.

[Kiro]

Before 1902 the name of the parish was written Elfdalen so I'm not sure it's just a translation thing.

Edit: Ok, never mind. It's definitely a translation thing: "The English name of the vernacular was introduced in Dahl & Koptjevskaja-Tamm (2005)."

Very recent too.

[hashmush]

More likely that they wanted the names to sound similar rather than being equivalent, and it's not that often one translates place names.