The unknow language you mentioned seem to me Norwegian in 19th century.
Some spellings are affected by Danish, and some stanza seem more Danish than
the others, though most of the terms are modern Norwegian. But the final
stanza is clearly written in Nynorsk, so this may be one of the songs
collected in 19th century at the time of building "new-Norwegian" language.
Where did you find it? It is an interesting sample of the time of Norwegian
language development.