Are you sure 'nett' is translated 'night'? Wouldn't 'just' be better?
"The song is written in an old version of Nynorsk (new Norwegian)"
Not really. It says jorda and not jordi, la not lata, ære, not æra. I think this is even within the current official (very Bokmål-like) standard for the most part.
The song is written in an old version of Nynorsk (new Norwegian)