at the claims of independence comes from the Catalan nation and not a political entity
There is no Catalan nation in a juridical or political way, and there has never been. You can talk about the Catalan nation as you can talk about the zombie nation, or the London people nation, but not in a juridical or political way. In that way, the only nation in Spain is Spain.
there's the Principality of Catalonia, established in the 11th Century
It was part of the Crown of Aragon, under the sovereignity of the King of Aragon. The term Principality of Catalonia was created in the 14th Century, not in the 11th, and it is just a juridical term to designate a territory's jurisdiction. The territory to which the Principality of Catalonia references were, again, a bunch of counties wih no political unity. Note also that the term "Principality of Catalonia" did not originated because it had a prince (Catalonia never had a prince). It is originated from "Princeps", a term from Roman times.
which would later expand into a personal union with the Kingdom of Aragon (led by the Catalan house of Barcelona, by the way)
One of the Kings of Aragon earned the Crown of Aragon because his grandfather was the King of Aragon, and the County of Barcelona because his father was the Count of Barcelona. So the County of Barcelona became part of the Crown of Aragon. This way the King of Aragon earned only the County of Barcelona, that had no political unity with the rest of the Counties that form today's Catalonia (another 7 Counties or so). All the territories possessed by the King of Aragon, including the County of Barcelona, were part of the Crown of Aragon.
A personal union means that two separate realms are ruled by the same king (like Sweden and Norway in the Swedo-Norwegian Union of 1810, or like Scotland and England in the original British union). Both realms remain independent and with their own laws and sovereignity. It remained a separate ordinance from both the Kingdom of Aragon and Spain up until 1716, when all of the Crown of Aragon's lands were stripped of distinction from the Kingdom of Spain.
All the King of Aragon's possessions, including the County of Barcelona and the rest of the Counties that form today's Catalonia (that had no political unit back then, it was a bunch of Counties) where called the Crown of Aragon. And they were all ruled under the rules of the Crown of Aragon and its sovereign was the King of Aragon.
As for Catalonians never fighting for independence, that is wrong too. A quick search reveals at least two instances of outright revolt in 1640and 1687
Those were not revolts for independence, those were revolts of the peasants against the nobility to stop their abuses. It has nothing to do with independence because it was not their goal. The sources of those articles you provide are from Henry Kamen's work (British hispanist historian that lives in Catalonia), and Henry Kamen said about Catalonia:
"Catalonia falsifies its history" and that "Separatism is a minority movement among Catalans. Most have been nationalist without being separatist".
as well as several formations of an independent or more sovereign Republic of Catalonia.
Quoting Barrentyna, an universitary Catalan rector in Barcelona that wrote "Historias ocultadas del nacionalismo catalán" (the hidden history of the Catalan nationalism):
"Catalonia has never been an independent political reallity"Pau Claris in 1640, proclaimed Catalonia as a Republic but only lasted one week, then he turned Catalonia to the king of France. In February 1873, Baldomero Lostau tried to proclaim a Catalan Republic within the Spanish Federal Republic but failed miserably. Colonel Macia proclaimed on April 14, 1931 the Catalan Republic, confusely linked to a union of Iberian people, and lasted a couple of days. Finally, on October 6, 1934, Companys proclaimed another ephemeral Republic within an imaginary Spanish Federal Republic which lasted for 10 hours".
And independent state of Catalonia has basis both in the existsence and history of the Catalonian nation as well the political and legal history of the region.
As I have shown, there is no historical basis for a Catalan independent state. Also, it never existed as a political unit outside Spain. And juiridically or politically (that is what we are talking about), it is not a nation and it has never been nation.