They aren't offensive names.
But you shouldn't glorify these names and it bay be pa dark part of our history (I am a german), therefore you should not spray there word by using such names and write in chat things like "Sieg Heil". I think and hope that are mostly children who write all that stuff, who don't know what they are saying, and i hope they will regret when they learn a bit in school, if it's not so and that are grown up people i only can feel sad for the humanity.
Fact is that the Nazis killed more that 11 million humans, compared to that it is nothing what may happened to some german POWs or other citizens after the war.
But i am not sure if this is the right forum for this. I think the actual best way to handle that problem with those guys in coh is to block them so that they write and write and that no one will listen to them. Like imagine it is war and no one goes there.