Oh true. How did I not get that :O.
so adding stuff like slot_faction_culture_1, slot_faction_culture_2, etc etc, and then changing every instance of slot_faction_culture to slot_faction_culture_1 or _2 or something, that would work?
(faction_set_slot, "fac_kingdom_1", slot_faction_culture, "fac_culture_1"),
(faction_set_slot, "fac_culture_1", slot_faction_culture, "fac_kingdom_1"),
(faction_set_slot, "fac_culture_2", slot_faction_culture, "fac_kingdom_1"),
(faction_set_slot, "fac_culture_3", slot_faction_culture, "fac_kingdom_1"),