I maintain that rebels have been broken ever since the original game came out. I'm actually shocked you are seeing so many Pan-nationalists and not A-Ls. I personally think that the CSA and USA should not be subject to the cultural union tag rules in general, much like the UK and USA not being subject to the same rules. For a democratic people to peacefully want to re-form a union that it so vociferously left so quickly is ridiculous. This business of suddenly so many CSA citizens wanting to re-form the union? The ACW is supposed to be modelling a large rise in CON such that the voting populace thinks that the USA is massively against their interests. For this to so radically shift? I mean, come on... Historically, if the CSA were to actually win, do you think they would have realistically reconciled their differences?? Had the UK intervened... or any other power there would have been a huge geopolitical incentive to maintain the status quo and prevent the USA from re-forming. I think cultural union tags need to be severely scaled back or be subject to more stringent requirements.
Nationalists should be scaled back within the unions too because in general the only reason why cultural unions were not unified is due to the monarch's selfish interests in maintaining his own fief. Why do you think the Frankfurt Parliament was such a watershed moment? Finally the German people were able to change the conservative order and request a unified nation state. This age is characterized by peoples wanting to unite in the face of conservative and reactionary forces, sometimes foreign, sometimes domestic. Likewise, in the odd event that reactionaries (nationalist) are able to set themselves free it should be EXTREMELY difficult to pull them back in. Cultural union should in general be viewed as "permanent" and undoing it as treason against the will of the people and require extreme measures to undertake. Similarly, if circumstances, albeit extreme, allowed Saxony to leave the NGF/Germany, then nothing sort of war should be able to put them back in the united state. What factors would cause them to leave? Either a massive feeling of discontent among the voters or foreign intervention. Either way, either of those two elements should be very difficult to reverse.
Some nations shouldn't be in a cultural union though just because they were personal unions of different cultural groups and had recently had legislation to solidify the nation state. I'm looking at you, UK... Scotland shouldn't be in cultural union with England. Scottish nationalism has been around for some time and even today we're witnessing a looming referendum on the maintenance of the UK. The Scots and English were also not culturally as similar as the wider Germans or Italians. The Anglo-Saxons and then the Normans thereafter of England had been viewed by Celtic peoples as invaders for many centuries. If by some way, Scotland was to be freed, I find it highly unlikely they'd so quickly run back into the arms of the English.
It seems there needs to be a higher threshold for all this nationalism nonsense. Right now, it seems like a giant mess to me. I've always wanted to tinker with the movements and rebels, but from what I've seen many of these elements are not exposed for modding.