The proposed content translation from nowiki to nnwiki gets wrong subdomain. For nowiki the subdomain is "no" even if the correct language tag could be "nb". This site has to variations of Norwegian called Bokmål and Riksmål. The longer explanation is that there are several variations of Norwegian, more than the two usually said to be "Norwegian" (four in fact). This has made nowiki retain the subdomain "no" as the Riksmål-community is quite large. Often the Riksmål variant is said to be a variation of Bokmål, but all word forms used in Riksmål isn't allowed in Bokmål so using "nb" language tag wouldn't be quite right - but still we are using it.
When the link is built it uses the subdomain "nb", that is the language tag, and it seems like that makes the content translation fail. One example is to use the page [[ http://no.wikipedia.org/wiki/Tonsåsen | Tonsåsen ]] at nowiki as an example and follow the redlink to [[ https://nn.wikipedia.org/w/index.php?title=Spesial:Innhaldsomsetjing&page=Tons%C3%A5sen&from=nb&to=nn&targettitle=Tons%C3%A5sen&campaign=redinterlanguagelink | the content translation page ]]. This link will fail with an error message "The "Tonsåsen" page could not be found in norsk (bokmål) Wikipedia". One reason that it isn't found could be that the subdomain "nb" is redirected to "no".