I think the anti-catalan feeling is summarised in the third quoted paragraph of the original editorial.

There is an increasing weariness over having to stand the angry look of those who continue to perceive the Catalan identity (its institutions, economic structure, language and cultural tradition) as a fault which prevents Spain from attaining a dreamed and impossible uniformity.

This is a jab against the Centralist Nationalists' myth of a unitary Spain without diverse national identities.

Catalans pay their taxes

Catalonia is a net contributor to the Spanish state

(without historical privileges);

I translated forales by historical which is a stretch but there was no way to do otherwise without inserting the long explanation which now follows.

In Spain fueros (I believe this may come from the Latin foedus) was the old name for a Royal Charter, given to newly incorporated towns, or to entire regions. The only surviving fuero is the one for Navarra, which is why the Autonomous Community of Navarra is actually called 'Foral Community of Navarra' and Navarra's 'historical rights' are mentioned in the appendix (transitory provisions) of the Spanish Constitution. As an aside, the only other notable use of fuero is in the Fuero de los Españoles, a sort of Charter of Fundamental Rights enacted by Franco in 1945 - here fuero as Charter is like the Carta in Carta Magna.

Anyway, the Basque Country used to have a fuero but it had been abolished. However, the Basque Autonomy Statute is inspired in the old fuero. As a result of this the Basque Statute has a different fiscal arrangement to all the other Autonomous Communities. This is what the editorial complains about when they say "Catalans pay their taxes without 'foral' privileges".

they contribute with their effort to the transfer of income to the poorest parts of Spain;

This is a common debate - the poorest regions of Spain are Andalusia and Extremadura. It is a common trope for Catalans to remind everyone that they are subsidising Estremadura with their taxes. This doesn't go down very well in those parts. Meanwhile, Andalusia has been complaining about a "historical debt" that Spain owes it, so if Andalusia is being subsidised by the wealthier parts of Spain this would be in payment of that debt. Or something - the point in each case is to propagate a myth of victimisation.

they face economic internationalization without the many benefits of hosting the State capital;

Madrid being the capital is both a blessing and a curse, and Barcelona envies the blessing without thinking they'd be cursed. People have been talking about giving Madrid a special status through a "Capital City Law" to address a number of problems but this never happens. Anyway, in this bag I should throw the football rivalry between Real Madrid and Barcelona. Supposedly Franco favoured Real Madrid and this continues to this day, despite the fact that Zapatero (being from Valladolid of all places) is a fan of Barcelona. Anyway, lately the President of FC Barcelona has managed to elevate himself to political leader, making well-received (?) political speeches about Catalonian independence. I kid you not. No wonder they say "Barça is more than just a club" - soon it might even become a political party :-P

they speak a language with more demographic weight than many official languages of the EU

true, Catalonia proper has about 6 million people, and the Catalan language is spoken by about 10 million people. However, Catalans have engaged in their own brand of linguistic imperialism and linguistic politics within the Catalan language family is a bit thorny. In Valencia, Catalonia's neighbour to the South, they call the language Valencian in an effort to escape Catalan cultural imperialism, and it is, of all political parties, the PP which most strongly protects this distinction between Catalan and Valencian. You would thing a party which nationally so strongly objects to Basque and Catalan would also object to Galician and Valencian and Majorcan but no, as Galicia and Valencia are PP electoral strongholds (or 'granaries of votes' as we say in Spain), the PP happily uses the Galician and Valencian languages (often bastardised as older PP politicians tended not to be very good at their local languages). Anyway, I won't go into more details of this, but suffice to say that the level of political silliness around the Catalan languages is quite high.

a language which, instead of being loved, is so often subject to obsessive scrutiny by the official Spanish nationalism

Bah, humbug. The real problem here is not the "official Nationalism" but the unofficial one. Ordinary Spaniards have a veritable mental block when it comes to Catalan and seem unable to function in the bilingual environment of Catalonia, where Catalans will, among themselves, hold bilingual conversations with some participants switching back and forth. So, the natural reaction of a Catalan speaker to being addressed in Spanish is to reply in Catalan as that would be socially acceptable among Catalans. But if the Spanish speaker is not Catalan but from elsewhere in Spain, they will think the Catalan speaker is being deliberately rude and "doesn't want to speak Spanish" where the proper reaction would be to politely say that you don't understand Catalan at which point the Catalan speaker will switch to Spanish (unless he's having a bad day in which case there will be rudeness all around).

In this connection, the Spain's Director General for Film, former MEP Ignasi Guardans, who is a Catalan wpeaker and used to be a member of the Nationalist party CiU, recently said that "people will rather see a film in Farsi than in Catalan" (well, he did say 'in Iranian' but we'll forgive him that). And I have to say I have seen films in both Farsi and in Catalan (with subtitles) and that once, given the choice between watching a Catalan film in the original version or dubbed to Spanish by the actors themselves, I chose the Catalan original, I would have to agree with Guardans - a film in Catalan will be seen by fewer people in Spain than a film in Farsi. He argues it is more important for encouraging the Catalan film industry to get films produced in Catalonia than to worry about whether American films are dubbed to Catalan (which is what Catalan politicians care about - and this is the kind of opinion that led to him being sidelined by CiU as an MEP candidate),

and they uphold the laws, of course, without giving up their peaceful and proven ability to withstand with civility.

We're not terraists like those Basques, we.

These days, Catalans think, above all, of their dignity; this should be known.

En un viejo país ineficiente, algo así como España entre dos guerras civiles, poseer una casa y poca hacienda y memoria ninguna. -- Gil de Biedma