There is a melodeon festival (really!) in Arseguel at the end of July and Artur Blasco who runs it will tell you everything else going on.

I spent ages tracking down Habaneres (generally associated with the Costa Brava) only to find them in the Pyrenees.

Then every single village festival (August 15th is a good day) will have something.

PM me if you want to know more.

Dave