This is pure greatness.
Banners in Catalonia are well done in Vanilla, but in Castille and León, they suck. Most of them are modern coats of arms with no Medieval significance. The problem, as usual, is the identification of a CoA wuth a piece of land, instead of with a family, which is what should be. In Mainland Europe, this it OK, but in other places, like in Castille, the control of families over large estates ("counties", in France) never really happened until the nobles got huge pieces of land in Andalusia, recently conquered from the Moors.
Still, you can use some of the XII-XIIIth Century great families for each "county".