Sorry, that link doesn’t lead me to any useful page. I can only judge by the languages which are already in there.
Your link, by the look of it, leads to a place where a user can provide new translations.
Now, it is totally possible that Plex is only looking for Nynorsk translations and is ignoring Bokmål translations. (Classic error for programmers which never heard about norwegian.)
There is actually a new metadata agent being written right now, which among many other things, is supposed to handle this little detail better. Take a look New Plex Media Server TV show/series scanner and agent preview
Until this one is finished and released, you won’t unfortunately achieve any improvement regarding norwegian language support for tv shows in Plex.
