Good question, Svätoslavka, I am not sure. Indeed it has nothing to do with what story is about.

I suppose to some degree, "Wikinger" and "Nordmänner" could apply also to Slavs, since we are also Northern Europeans by origin and there were Slavic vikings also (Varangians, Rus', Jomsborgs and Vinds), so it can still be tolerated IMO in general.

But this story indeed is Slavic tale and not Viking saga.