Colonies im Bellum Crucis

[Varangon]

I have been playing BC for years now and it's definitely one of the best mods afaic. However, there's a minor thing I'm interested in.
When I build colonies, like Venetian, Catalan, Turkish, Arab, etc, there's a building bonus which says:

Religion Conversion Bonus: -1 (or -2/-3/-4 depending on the level of the building).

I know it should spread Islam or Catholicism, but it works only sometimes. Most of the time, it doesn't.

I checked the files and was shocked to see that there are no lines specifying the religion of these building at all.

Here's the code:

building quartiereturco{

    levels quartiereturco1 quartiereturco2 quartiereturco3 quartiereturco4
    {
        quartiereturco1 requires factions { northern_european, mesoamerican, eastern_european, greek, southern_european, moors, egypt, zenghids, timurids, nativeindian, } and hidden_resource horde_target and hidden_resource genovesi
        {
            capability
            {
    trade_base_income_bonus bonus 1
                trade_fleet 1
                religion_level bonus -1 requires factions { northern_european, mesoamerican, southern_european, eastern_european, greek, } 
                law_bonus bonus -1 requires factions { moors, egypt, zenghids, timurids, nativeindian, } 
            }
            material wooden
            construction  1 
            cost  2000 
            settlement_min large_town
            upgrades
            {
                quartiereturco2
            }
        }
        quartiereturco2 requires factions { northern_european, mesoamerican, eastern_european, greek, southern_european, moors, egypt, zenghids, timurids, nativeindian, } and hidden_resource horde_target and hidden_resource genovesi and not building_present_min_level quartierearabo quartierearabo2
        {
            capability
            {
    trade_base_income_bonus bonus 2
                trade_fleet 2
                religion_level bonus -2 requires factions { northern_european, mesoamerican, southern_european, eastern_european, greek, } 
                law_bonus bonus -2 requires factions { moors, egypt, zenghids, timurids, nativeindian, } 
    recruit_pool "turkoman infranty"  1   0.25   1  0  requires factions { moors, egypt, zenghids, timurids, nativeindian, }
            }
            material wooden
            construction  2 
            cost  4000 
            settlement_min city
            upgrades
            {
                quartiereturco3
            }
        }
        quartiereturco3 requires factions { northern_european, mesoamerican, eastern_european, greek, southern_european, moors, egypt, zenghids, timurids, nativeindian, } and hidden_resource horde_target and hidden_resource genovesi and not building_present_min_level quartierearabo quartierearabo2
        {
            capability
            {
    trade_base_income_bonus bonus 3
                trade_fleet 3
                population_growth_bonus bonus 1
                religion_level bonus -3 requires factions { northern_european, mesoamerican, southern_european, eastern_european, greek, } 
                law_bonus bonus -3 requires factions { moors, egypt, zenghids, timurids, nativeindian, } 
    recruit_pool "turkoman infranty"  1   0.25   1  0  requires factions { moors, egypt, zenghids, timurids, nativeindian, }
    recruit_pool "turkoman foot archer"  1   0.25   1  0  requires factions { moors, egypt, zenghids, timurids, nativeindian, }
            }
            material wooden
            construction  3 
            cost  8000 
            settlement_min large_city
            upgrades
            {
                quartiereturco4
            }
        }
        quartiereturco4 requires factions { northern_european, mesoamerican, eastern_european, greek, southern_european, moors, egypt, zenghids, timurids, nativeindian, } and hidden_resource horde_target and hidden_resource genovesi and not building_present_min_level quartierearabo quartierearabo2
        {
            capability
            {
    trade_base_income_bonus bonus 4
                trade_fleet 4
                population_growth_bonus bonus 2
                religion_level bonus -4 requires factions { northern_european, mesoamerican, southern_european, eastern_european, greek, } 
                law_bonus bonus -4 requires factions { moors, egypt, zenghids, timurids, nativeindian, } 
    recruit_pool "turkoman infranty"  1   0.5   1  0  requires factions { moors, egypt, zenghids, timurids, nativeindian, }
    recruit_pool "turkoman foot archer"  1   0.25   1  0  requires factions { moors, egypt, zenghids, timurids, nativeindian, }
            }
            material wooden
            construction  4 
            cost  16000 
            settlement_min huge_city
            upgrades
            {
            }
        }
    }
    plugins 
    {
    }
}

How is this even possible? Even if it was possible for the engine to read negative values of religion_bonus, how is it possible for it to know which religion to increase when it's decreasing your faction's religion?

[Virian]

Doesn't it simply increase the second largest religion?

[Varangon]

Not in my case. It doesn't do anything most of the time, except spawning a rabbi when I have the Jewish colonies.