I have read this topic with much interest... It is sad that so-close living nations and ex-allies have so much different view on their common history.
I wish we - Polish, Belorussians, Ukrainians and Lithuanians could come to agreement about our past. Especially because our cooperation brought us much prosperity, while misunderstending - so many tragedies. What is more important, any of the successes of the Union couldn't be achived if we acted separately, so we shouldnt deny others part in this great deeds. There wouldn't be a Grunwald's, Orsza's, Chocim's, Kirchholm's or Vienna's victories, if there weren't lithuanians, nor belorussians standing together by one side.
About Vilnius: it was lithuanian city originally. Through many years of Commonwealth it become more polish than lithuanian, because of immigration and polonization of lithuanian nobility. After WWI it was almost completely polonized lithuanian city in the heart of lithuanian lands. Polish invaders, who seized Vilnius in 1920, were Poles, who were born there, or Poles whose ancestors were belorussian or lithuanian as well. Does this have any meaning now? They all fought for land that belonged to their fathers and mothers. I dont see any reason to have quarrel about it.
Vilnius is lithuanian and lithuanian should stay. I think of this in terms of enclosed wheel of time: the whole story returned to its beginning.
How can this be solved in game? There should be mod with separate polish, lithuanian, belarussian and ukrainian civilizatons. I don't think that'll be a serious problem if some city names will be in one time belarussian, polish or lithuanian as well - the same thing had happen to many middle-east or mediterranean cities, and nobody complains (e.g. Byzantium, Constantinople and Istanbul).
There might be a commonwealth scenario, and in such case Republic(Commonwealth) of the Three Nations civilization should have all - polish, lithuanian and rus' cities as well. Interesting would be a scenario, in which all nations start separated, but can be unified, or simply have positive attitude modifiers that will make diplomacy between them much easier than with other neighbours, and with great chance for permanent alliance.
Greetings to all of you (pozdrawiam was serdecznie)