Looks pretty good from what I've played. I've noticed some issues in my playthroughs:
-The Combined Syndicates event to "claim" New England uses the wrong province ids- they seem to be Alaska.
-If the Soviets assume power peacefully, there doesn't seem to be an event to give them cores over Russia proper. There is an event in the files (757000 in Russian Revolution file) for this but it is not triggered by anything. I would say have it triggered by the events that have the constitutional changes or the "final step" bit. I personally did the latter but found I only got cores on the northwestern portion of Russia as a result.
-The following are more of a nitpick, but the German Union has Rudolf Rocker as a possible minister, specifically its HoS. I think an event should be fired to remove Rudolf Rocker from the CSA ministers if this occurs, that is the creation of the German Union. On the same note the Karl Liebknict is missing a picture as a minister for that nation.