I doubt Relic will chance the name.
"Obersoldaten" is actually a pretty good name for them! In german "ober" is basically a word for something elite or better/best.
"Ober" just means that the grade of the soldier is higher than of others. It also refers to the word "oben" which freely translated means in englisch "above". A german military rank for example is "Oberst".
It is a legit german word.
You are right. Still, obersoldat makes no sense in this context. All other units titel refers to their rank, function or type (vehicles). Obersoldat violates this rule.
Honour Guard is bad idea either. There was no such formation in the Wehrmacht. It sounds like a parade formation, not like elite solidiers or veterans. Besides Guards is alread taken.
Approciate would be something like:
(Ostfront) Veterans
Sturmtrupp