> I don't know how similar Icelandic is to other Nordic/Scandinavian languages so maybe a speaker of these languages would have been able to identify the lyrics

Not likely, Icelandic has kept much closer to old norse in grammar and phonology so sounds nothing like continental scandinavian (also much prefers neologisms to loanwords, but that’s maybe less of an issue for song lyrics). You’d have had to ask specifically icelanders, maybe faroe islanders as a last recourse, but there’s a lot less of the latter than the former.