I thought this was already possible, cf vanilla:
Code:b_cluny = { coat_of_arms = { data = { 0 4 12 45 2 2 2 0 0 19 2 1 3 0 0 19 2 1 3 0 0 19 2 1 3 } religion="catholic" } }
That's still a random engine COA. I mean an actual b_amsterdam.tga coat of arms.