Instability isn't all that bad. At the very least it gives a reason for people to stop nagging about lack of social mobility because chaos brings about shifts in social class. Not entirely sure it makes them stop though.
I honestly don't understand people that think an actual war is impossible of 'over-dramatic'. If you had told an Ukrainian they'd be at (proxy) war with Russia two years ago, they'd have laughed in your face.
There's a difference between Russia formenting a separatist republic directly on its border, and them somehow sparking an economically driven regionalist movement all the way across Europe. May I also remind you that Ukraine almost won before Russia intervened directly from its border?
Plus I'm a little dubious on the prospect of Spain sending in the army against Catalonia. And if they did, it's not like the Catalans have any weapons.
Spain won't let the Catalans go, I've lived a long while in Galicia and found no secessionist feeling. While there too a majority of the population speaks Galician and not Castillian. (To be fair, Galician is similar and almost everybody I ever met knew Castillian as well.) Spain is in the ****hole and has been since before Franco left power, breaking it up won't help anybody.
I'd prefer they actually had a reason, and it extended more than linguistic difference. Spain has been united for hundreds of years and I see no reason for it to suddenly not be, Catalonians need to understand that they are part of something bigger than just Barcelona and its outlying areas. By CK2 standards they've been de jure part of Spain for at least 400 years by now.
I don't see that happening. Unless somebody can impartially coordinate the resources of countries towards large projects like dams or rail networks (which would have cross-border effects), a splintered Europe would be inefficient and a patchwork of rich urban areas and poor rural hinterlands. Kinda like China or India.
I'm of the belief that it's better for the regional economy as a whole if the more productive regions have to support poorer ones. For example If Wales or Yorkshire became independent from the UK, they would be almost completely ineffective as nations and become like Ireland, resorting to tax havenning and other fake industries to survive, and contributing little to neighbouring countries. But within a larger country that supports them, they have access to public services, transport and education that are effectively paid for by people who can afford it.
I support catalan independence on simple principle. Any form of fracturing of nation states is fine in my books. I'm well aware of the economic and social problems it causes. But I just like the idea of Europe returning to a massive patchwork of inane little principalities too much. If it were up to me we'd split Norway back into the old Jarldoms too.