Railroading in what way? Saying 'the United States area is will be scripted to being the first colony in the New World to declare independence' is the kind of aggravating sort of scripting that's best to avoid. Instead, the game should be able to simulate reasons that a new world colony might be able to declare independence (a largely settled area that has the kind of local prosperity and the idea that it can defend itself on the own, colonists being unhappy with any policies that the crown is passing, and how many Enlightenment-style liberal 'administrative techs' have spread to them).
The Napoleonic Wars as such is really hard to simulate, but it wouldn't be done with saying 'welp, this is a 6/6/6 general who spawns with doomstacks' but instead, first setting it up so that there are pro-war parties in the world's first major revolutionary liberal republic who want to create sister republics, defeat the nation's historic rival and/or annex similarly-cultured pops during the rise of nationalism. Then also factor in some kind of revolutionary factional system where you have the military forces potentially coming out on top - so maybe you can see something similar happen, but also a lot of other plausible possibilities.