Glad everyone likes it! I went with...
Standard English for Swedish. Because this is from Emil's perspective.
Northern English for Norwegian. Because it's understandable, but has a notably different accent and the odd different word here and there. It's also kind of halfway to what I chose for Danish, which is what Minna said about Norwegian on her language chart.
Glaswegian English for Danish. Because it's more or less understandable when written down, but sounds like something from Mars when spoken by a native speaker
Dutch for Icelandic. Because it's closely related to English and an English speaker can pick out the odd word, but it's mostly that incomprehensible language spoken by those guys over the sea.
Welsh for Finnish. Because it's wildly incomprehensible to an English speaker, but recognizable as what those weird people next door speak