I started with Olot with this as the only file added. Had "Add players to playable teams" on. Spain as the only country selected. All other catalan teams seem to have spanish regens in their youth teams. Olot have a bunch of russians:
As far as I remember reading about it - they do allow for Valencian, Andorran, Balearic and French Catalonia players to join as long as they speak Catalan.