I don’t argue Left vs. Right so much as pro-EU big central government versus decentralized government anti-EU.
I’m more capitalist than socialist but not crony capitalist fake Left like Canada’s Liberals or Tony Blair’s brand of Labor Party that Corbyn trounced in recent leadership contests.
There’s a lot of lefties in Catalonia but Catalonia is the wealthy part of Spain like northern Italy bailing out other parts and being crushed by the EU regulations etc. etc.
The League of Northern Italy is more to the Right but their fight is the same as the Catalan Left.
But the pro-independence Catalonian politicians are mostly pro-EU (similar to the Scottish National Party). Those of them who are anti-EU are left-wing extremists (i.e. communists or near-communists).