Cool, I'm glad a lot of people responded - this scenario is my favorite of all time, by far. Actually, I was trying to read through the whole thread and kinda gave up, so even if this hasn't been done in a while... I had three observations about the scenario.
Firstly, IRL in modern times, Japan's productive power is almost equal that of the United States, despite it being so small. If they wanted to, they could update their "Self-Defense Force" and become a military power on par with the United States within two decades (that's not my research speaking there, though). At the moment IG, even with Japan being almost entirely made of hills and mountains, it can't compare to a theoretical civ with cities occupying the general area of the United States.
Secondly, and much furthur back in history, the union of Poland and Lithuania produced one of the most powerful states in the history of Eastern Europe, until its defeats by (and my history is somewhat vague here, so forgive me if I'm using the wrong polity) the Tsardom of Muscovy. IG, if one were to recreate this union, one would essentialy only add Riga to Poland's territories, and this couldn't really compete with any bordering civs.
Thirdly and lastly: excluding the Middle East (heh), Russia (and to a lesser extent Central Asia) has enough oil to become the supplier of Europe and developed Asia. Since the IRL causes of this not already happenning won't necessarily occur in-game, it strikes me as a bit odd that pre-placed Russia and Siberia combined have something like one or two oils (Although at the moment I'm between eyeglasses, and I could've missed a couple).
As a general caveat, I've not exhaustively play-tested these things to come to my first two observation's conclusions, but I did look at the world map, and I did calculate terrain values for pre-placed and theoretical cities - although again, not very exhaustively. Also, there are some things Ive inferred being attempted that might be at crossroads with implementing my observations.
Mostly I just wanted to point these things out, because they've been nibbling at the back of my mind for some time now. Best of luck with the new additions to your team, TETurkhan!