We are putting the fort back in Vilnius for the next patch.
As for province names:
It is of course always complicated to decide what language a province name should be in. The base name we try to have in whichever is the norm in English (but our map is old and not always consistent in that, and not all historical places have standard names in English). The game currently does support provinces changing names depending on who owns them though so if you supply us with a list of the Lithuanian provinces with Lithuanian names I am sure we can adapt them
As for province names:
It is of course always complicated to decide what language a province name should be in. The base name we try to have in whichever is the norm in English (but our map is old and not always consistent in that, and not all historical places have standard names in English). The game currently does support provinces changing names depending on who owns them though so if you supply us with a list of the Lithuanian provinces with Lithuanian names I am sure we can adapt them