I don't even know if it's going to be fixed. Paradox hasn't acknowledged if this is WAD or not. Some players have posited that it is Spain trying to block England and France from Chesapeake, but the opportunity cost doesn't justify that explanation. Others have said it's a reasonable course of action as long as Spain moves its capital to the Bordeaux node. The AI never does this though. Even if it did, I doubt competing for trade against Portugal in Carib, England in Chesapeake, and England, France, and The Netherlands in Bordeaux yields more profit than cooperating with Portugal in Gold Coast and Carib and competing against Portugal in Seville.
It's both to a degree. Based on what someone(I don't recall who) told me about the missions, Castile is getting missions to colonize in the Chesapeake(specifically Newfoundland and Thirteen Colonies) relatively early. Therefore, by the time a British or French AI gets there, the seaboard is mostly yellow. In my most recent game, Spain only put 3 or 4 colonies in Carib and then just went crazy on the Thirteen colonies. I rushed to torch them, but they were hell bent on getting colonies on the Eastern Seaboard. When I gave up, the game was around 1610 and Spain hadn't touched Central America or South America.