That might be accurate for the balkans but not for countries like Belgium and Netherlands. It was the invasion of Belgium that provoked Britian to enter world war I, so I think the cultural annexation of Belgium without declaration of war is not accurate.
Also, during that time period, if a small piece of territory was captured, there was no way it would be allowed to go back to the other country (i.e. Alsace - Lorraine).
Also I hope you are making some changes to the cities. The main problem is that some don't match the time period. For example Anchorage wasn't even founded until 1915. I don't think Prince Rupert, Fairbanks, or Whales were around either. The populations are too high in almost all continents (except Europe). Even in Europe a few cities (like Christiana) are too big.
If you want a good site for population statistics during various time periods go here:
http://www.library.uu.nl/wesp/populstat/populhome.html
As for the resources I would recommend removing horses and iron entirely as they were very common by 1890. I can see if you want to keep iron but definately remove horses.
I think you should make riflemen have equal attack to defence. The only reason they would be better on defence would be because of fortification or terrain, and both of those already give them a defensive bonus.
China should NOT have samurai. Japan should not have cossacks and I doubt they had much cavalry either. I don't know if you or Caliban put those in, but I will complain about it anyway.
You need a neutral civ, for Mongolia, Afghanistan, Ethiopia, and other unaffiliated countries. Maybe rename "South America" to
neutrals and include those.
Mexico be independant. This is just coming off the liberation of Mexico after it was conquered by the French, so it would add flavour to have an independant Mexico.
It would actually be ideal if you had more interesting division in South America. This was a short while after the Bolivar wars and the subsequent breakup of Colombia. There were lots of wars and such in the time period so it doesn't make sense to have them in the same civ.
Chile was at war with Peru and Bolivia until 1884. (Chile won)
Colombia owned Panama but lost Venezuela and Ecuador in 1830 (hostile breakup)
The Brazilian emperor went into exile in 1889. Brazil had won a war with Argentina and Uruguay against Paraguay in 1870.
Ideally these would be the civs:
Chile
Peru + Bolivia
Colombia
Venezuela + Ecuador
Brazil + Argentina + Uruguay
But that is too many so I would divide according to "the enemy of my enemy is my friend"
Venezuela + Ecuador + Peru + Bolivia
Chile + Colombia + Brazil + Argentina + Uruguay
I would join central America with Mexico or the Colombia team (probably Mexico)
Put more jungle in South America, right now the Amazon looks a little sparse.
Put in the Caribbean islands like Trinidad, Martinique, etc. They were all relatively valuable colonies.
Also be careful with Africa, many of those cities may not have been founded yet or be much smaller. I would put more focus on South Africa due to the Boer war. You could put the Boers with Germany but that would cause a war, which isn't accurate, so you might want to make them rebels or something.
Anway enough rambling for now. Don't take this the wrong way, the more I want to play a scenario the more I will critisize it.
I hope you release the new version soon!
Good scenario though (I am attempting to create a greater German Reich in Europe). 
