When I create an item by linking an article in nowiki to an article in another wiki, the label that's taken from the nowiki article is placed in the language code 'no' rather than 'nb'. See example here: https://www.wikidata.org/w/index.php?title=Q21139240&action=history

The 'no' language code should never be used in Wikidata. Whenever something is added in 'no' it should be addid to 'nb' instead.