More names

[Narvait]

I would use
Vyting(i)s for lower Noble (baron)
Konagis for Count

Historically that is it. I dont know of Prussian ruler having power over more than one ingame province.

So high chief would be high/big Konagis (from root Dydis/didzhus or similar).
King/Emperor could be from Vald- something. Or derived from Caesar in some way. Keizaris? Or Charlemagne. Karalis/Karolis.

 

[Herr Doctor]

I know but I used Lithuanian Wiki when I was looking for localities and dynasties (I think they are still in the Germanised version at this time in the mod though-because I haven't had the time to do this minor overhaul) which strictly goes for Lithuanian style spelling and thus so did I, in the names as well.

Yes, I understand, Lithuanian sources are best here. But replacing v with w won't be a big deal. IMO it would help to distibguish both West and East Balts a bit.