In general left republican Catalanism has looked favorably upon the Roma. In north Catalonia around Perpignan they are the only people who speak Catalan as a first language.

It seems likely that Orwell may have been confused as he didn't speak much Catalan (great book though , it's why I got my PhD in Catalan history!). I believe they were able to compete as a "nation" in the 1936 popular games but I should check that before I state it with certainty.

I have come across Romany people serving in the international brigades which suggests they felt somewhat alienated by "Spanishness" but supported the cause of the republic. When you consider the alternative, it makes sense to do so!

I cannot speak for Catalan nationalism's view of the Roma, but Republican Spain offered little prospects for Roma people. Republican national identity, while more inclusive than previous incarnations of Spanish nationalism, was still heavily Castile-focused. Much Republican propaganda made political capital out of the idea that Franco's forces were "foreign invaders". The most famous example of this is in the Spanish Civil War song "Viva la Quinta Brigada", also known as "Ay, Carmela!"

In the song, the chorus goes : "Luchamos contra los moros...!": We fight against the Moors. They are also referred to as "fuerzas invasoras"... foreign invaders.

Obviously, the Moors and the Roma are not the same people, but it gives you a sense of the racialized representation of the Nationalists. While it is true that much of Franco's forces came from Morocco, it was an oversimplification to refer to all of his forces as "moros". Republicans were not immune from Spanish racism.

Source: Sandie Holguin, "Creating Spaniards: Culture and National Identity in Republican Spain", Madison: University of Wisconsin Press, 2002.

Viva la quinta brigada, performed by Rolando Alarcon: https://www.youtube.com/watch?v=Fko5fYIBJFU