CB Shields and the AI
Paradox will have to correct me if I'm wrong, but CB shields are not just about political claims to lands.
First and foremost, CB shields seem to represent a historical direction of expansion for most countries in the game. Russia gets CB shields on all kinds of territories that correspond to certain territories she took historically. That way, you get that ever useful Casus belli automatically, and can wipe out the Hoard and Astrakhan quickly.
Secondly, they represent your core provinces. Since the game covers such a long period of time, it is reasonable that if Russia grabs Tula from the Poles, it will be a core province by 1792. Since CB shields rea not dynamic in the game, you have to plan for 300 years worth of CB shields. (more on this later) If someone took that away from Russia, the Czars would have casus belli forever to get it back. That makes some sense, but not 100% sense.
Third, it is a tool to get the AI to be smart. It is much easier to fight a war when you have casus belli. So, the AI will attack where it has CB shields. This keeps France from trying to conquer Ireland, while leaving Franch-Comte in Spanish hands. This keeps the AI acting semi-historical.
Fourth, CB shields are used to provide sources of continuing conflict. For example, many provinces have several countries who have a CB shield on them. That keeps things interesting and lively, no matter who owns the province. With human players, this isnt necessary, but the AI needs to have a catalyst for fighting wars, aside from BB ratings.
With all this in mind, Cb shields are not just about "the people in XYZ speak ABC language, so EFG country gets the CB shield there". It is all about related factors, some of which are strictly for gameplay and have little bearing on historical basis.
If we really wanted to revamp the CB shield system, you have to have dynamic CB shields, that changed with the length of time a province is owned by its current owner. I DO NOT suggest letting players and teh AI renounce Cb shields, as you will quickly see no conflicting CB shields in Europe after 100 years. Perhaps, if you hold a terriroty for 100 consequetive years, then you get a CB shield for it and remove any others there. For example, if I own Wessex as France for 100 years, then maybe I get a French CB shield there, and remove the English one. Of course, that has it's on set of problems that go with it. But the idea of dynamic shields is sound to a certain extent.