The problem is
@Yaarel, you are going about things backwards. You are pointing to the Rhennee and their association with real world Romani, and claiming that the same applies to Norwegians. But, you've skipped a LOT of steps there.
For one, we can look at real world bigotry towards the Romani and then compare that to the text in Greyhawk. The texts line up nearly perfectly. The original writers of the Rhenee basically took all the bigoted language from the real world and transplanted it into Greyhawk. ((Note, I am NOT commenting on intent here. Not in the slightest. Simply on what was done)) The same thing happened with the depictions of orcs in the game. The identical language was appropriated to describe orcs as was used to describe blacks. That's why it is so problematic. There's a clear line here from the real world verbiage to the verbiage used in the game.
There is not, however, a clear line showing that Norwegians are being negatively depicted in the Greyhawk texts. No reasonable observer thinks that Norwegians are Nazis. There is no program of discrimination against Norwegian peoples that I'm aware of. AFAIK, Norwegian people are not being lumped in with Nazis. Actual Nazis are being lumped in with Nazis, and some of them happen to be Norwegian, but, that's a totally different issue. Thus your issue with worries over Nazis and affiliated groups appropriating Viking cultural elements.
But, again, this isn't what's happening here. No one is going to equate Thillonians with modern day Norwegians. None of the language used in the game connects Norwegians to Nazis in anything but the most oblique way. You need to show that the language used to describe these in game elements directly harm anyone before you can claim that they need to be changed.