When a sim has the singing skill they can sing folk-music. There's been a small translatation error which means that instead of "folkemusik" with an "e" between "folk" and "musik" it just says "folkmusik" (picture 1) which is not a word.
My sim is currently at level 3 so I might not have unlocked all of them, but so far she can sing "Lille Peter Edderkop" (Itsy bitsy Spider), "Fra den Fjerne Mælkevej" (Twinkle Twinkle Little Star) and "Bro Bro Brille" (London Bridge is Falling Down). Lille Peter Edderkop is fine and Fra den Fjerne Mælkevej is seemingly the Danish equvilant of Twinkle Twinkle according to a google search, so that's fine too.
There has however been a mistranslation of London Bridge is Falling Down (picture 2). It was probably made because when you type "London Bridge is Falling Down Danish" into Google the wikipedia page for "Bro Bro Brille" pops up. Bro Bro Brille has a completely different melody though, and the correct translation for "London Bridge is Falling Down" is "Knippelsbro går op og ned"
To summarise:
"Folkmusik" needs to be changed to "folkemusik"
"Bro Bro Brille" should be changed to "Knippelsbro går op og ned"
