Why is the Mexican Empire so big, because in 1861, Mexico was not an empire, but a republic; also, they went from the Rio Grande to North Guatemala, just like today, same borders as the current. New Mexico belonged to the United States. You are probably confusing the borders of Mexico with the ones in 1821, which were not so in 1861. All those nations in Central America were under control of Mexico in 1821, but in 1823 they all declared independence. Panama was controlled by Columbia and Venezuala was its own country. Also, Benito Jaurez was the President of Mexico from 1858 to 1864, to which King Maximillian von Bavaria replaced him, and the Second Mexican Empire was established. Also, France and Britain are at war, which is totally inaccurate, they had indifferent relations to each other at the time. Also, France and Britain was friendly to the South and unfriendly to the North, it is the opposite in this mod. In addition, why is the CSA an absolute monarchy??? It may be because you took it from the Cherokee Tribes, who can't be a Republic, but what do I know?
As for Europe, the German Empire was established in 1871, but from 1848-1871, they were a Constitutional Monarchy, the Kingdom of Prussia, having the same flag as the vanilla version of the game. Here's a map:
http://en.wikipedia.org/wiki/File:Ac.prussiamap3.gif.
Norway is its own country as well.
But MOST IMPORTANTLY: focus on separating the Mexican Empire into its true form, using emergent factions to fill the places that don't have factions, also make sure Panama and Columbia are one country.
The Emperor of France is Napoleon III, not Napoleon XVI.
Why is France and Britain hostile to Russia? They love each other.
Also, the Russian Empire controlled Dagestan, Georgia, Azerbaijan, and Courland, this game says differently.
I could be an ACW mod team historian, if you want.
PS Why do you not ever get any regular infantry for the first 30+ turns before researching the tech that allows it? Fighting with mere militia isn't very fun when you're Union and the Confederates have regulars.