by bigloo33
More experienced players can probably answer better than me, but historically, it was found that the Russian side had a slight advantage, overall. This was balanced by bidding for sides, and the US side being able to place some additional influence, before starting the first headline. The optional cards were released to rebalance the game, negating the need for bidding/extra influence. As far as I know, judging from comments from more experienced players, the optional cards correct any imbalance.Completely separately, the Civil War Variant, is just that, a variant. Try it or don't, but it is completely separate from the base game, and its balance. I personally have never actually tried it, but from comments here it shifts the balance greatly, but gives a different experience.
Hope that helps.
PS: I will take you up on your Polis offer. Been following your posts there. Only one game under my belt, and felt very lost at sea (playing the Athenians to complete the pun). People have compared its depth to TS, so it is intriguing. I would be curious to see what you think of TS. The depth here is remarkable, but the rules are relatively straightforward, after a play or two.