I assume if you remove these red entries from the edb, this method would work also.
Code:
cannon_foundry city requires factions { northern_european, middle_eastern, eastern_european, greek, southern_european, } and event_counter gunpowder_discovered 1
{
convert_to 2
capability
{
recruit_pool "Elephant Artillery" 0 0.25 2 0 requires factions { timurids, }
recruit_pool "Musketeers" 0 0.5 2 0 requires factions { england, france, spain, portugal, milan, venice, } and hidden_resource Aor_Catholic
recruit_pool "Janissary Musketeers" 0 0.5 2 0 requires factions { turks, }
recruit_pool "Reiters" 0 0.5 2 0 requires factions { hre, } and hidden_resource Aor_Catholic
recruit_pool "Spanish Dragoons" 0 0.5 2 0 requires factions { spain, } and hidden_resource Aor_Catholic
recruit_pool "Cossack Musketeers" 0 0.5 2 0 requires factions { russia, } and hidden_resource Aor_Orthodox