So Rousillon wasn't a part of Septimania?
Eeeh, that map makes Roussillon a part of "Visigoth". Superpose it to a map of the Catalan Counties and you'll see. The small tip at the south? That's Cap de Creus. Catalonia ends some 2km north of it, and in this map the line extends far north, up to Salses.
However, internet found maps can be a tad incorrect. I'll give you that Roussillon was indeed a contested area and I could have been wrong there. I'll need to recheck my sources.
Oh, and you are right, it wasn't a feudal system yet. The title of count of Barcelona and the "maquis" of the Hispanic mark weren't titles you could simply inherit. The king could give it to someone he liked. And I've said somewhat independent. It was de facto independent, not de jure. Why? Because it was an integral part of the frankish empire, what the coudts did was a betrayal.
Feudalism was a process, not an overnight phenomenon. Even if Catalan feudalism did develop faster than in other places, it had some gradual setup. Private inheritance of public offices was one of them. Borell II did inherit his county from his father, and he left it to his son. Inheritance of titles was a thing already, although not on paper, and the king just confirmed the appointment made by the father. That's what we discussed in another thread just the other day. As for your insistence on "de jure", yes, it was in theory part of the Frankish kingdom, but when it's been 200 years since anyone has claimed it, proclaimed it or reclaimed it, the "de jure" phrase becomes meaningless. Especially here in CK, where de jure means "it is of course, by all means, rightfully ours and we'll take it now, anytime", which is not what happened.
As for "betrayal", Borrell II might have been a traitor, but that's not the point, we're not judging his actions. The point is: after this "betrayal", was Barcelona independent? And the answer is yes, we both have said it.
The fact that Borrell II felt entitled to proclaim he didn't owe anything to the King of the Franks and get away with it proves two things:
1- The concept of privative, private domain over a county, formerly propriety of the State, was already seen as such by former "public administrators".
2- The King of the Franks was powerless, or didn't want, to do anything about that.
I'll remember you that Borrell II's independence was just one more of a series of "de facto independences" that plagued Occitania between the years 900 and 1200, in the broader context of feudalisation.
And Borrell II did care about Rousillon being part of "Gothia". I found in this book, and he seems to be a somewhat good catalan historian (although a tad nationalist, but it's pretty normal among historians in Catalonia, and that makes them somewhat worse, but that's another story)
Salrach is a serious historian. Nationalism is quite spread among historians everywhere, by the way. It's a plague we just can't get out of, it seems. I'm guilty of it sometimes too.