I'm wondering how exactly since some Norscans can interact normally with outsiders. Would you be able to for example, accidentally insult their gods or something else.
In the end it could also just come down to language barriers and cultural differences. Words have many meanings, which would be especially true for the two languages at hand, Reikspiel and Norse, who are said to stem from the same root, therefore are related and could be expected to share many words.
Over the course of thousands of years it could be expected that some false friends develop.