linguist_bonus_culture_effect

linguist_bonus_culture_effect = {
	if = {
		limit = { exists = scope:$CULTURE$ }
		if = {
			limit = {
				any_culture_global = {
					exists = culture_head
					has_same_culture_heritage = scope:$CULTURE$
					NOR = {
						has_same_culture_language = scope:$CULTURE$
						has_same_culture_language = root.culture
						AND = {
							exists = scope:target_court_language
							has_same_culture_language = scope:target_court_language.culture
						}
						AND = {
							exists = scope:ling_cul_1_bonus
							THIS = scope:ling_cul_1_bonus
						}
						AND = {
							exists = scope:ling_cul_2_bonus
							THIS = scope:ling_cul_2_bonus
						}
						AND = {
							exists = scope:ling_cul_3_bonus
							THIS = scope:ling_cul_3_bonus
						}
					}
				}
			}
			random_culture_global = { # Find a culture that speaks this language natively
				limit = {
					exists = culture_head
					has_same_culture_heritage = scope:$CULTURE$
					NOR = {
						has_same_culture_language = scope:$CULTURE$
						has_same_culture_language = root.culture
						AND = {
							exists = scope:target_court_language
							has_same_culture_language = scope:target_court_language.culture
						}
						AND = {
							exists = scope:ling_cul_1_bonus
							THIS = scope:ling_cul_1_bonus
						}
						AND = {
							exists = scope:ling_cul_2_bonus
							THIS = scope:ling_cul_2_bonus
						}
						AND = {
							exists = scope:ling_cul_3_bonus
							THIS = scope:ling_cul_3_bonus
						}
					}
				}
				save_scope_as = $CULTURE$_bonus
			}
		}
		else = {
			random_kingdom = {
				limit = {
					exists = holder
					NOR = {
						holder = root
						AND = {
							exists = scope:target_court_language
							holder = scope:target_court_language
						}
					}
					holder = {
						in_diplomatic_range = root
						culture = {
							NOR = {
								has_same_culture_language = scope:$CULTURE$
								has_same_culture_language = root.culture
								AND = {
									exists = scope:target_court_language
									has_same_culture_language = scope:target_court_language.culture
								}
								AND = {
									exists = scope:ling_cul_1_bonus
									this = scope:ling_cul_1_bonus
								}
								AND = {
									exists = scope:ling_cul_2_bonus
									this = scope:ling_cul_2_bonus
								}
								AND = {
									exists = scope:ling_cul_3_bonus
									this = scope:ling_cul_3_bonus
								}
							}
						}
					}
				}
				holder.culture = { save_scope_as = $CULTURE$_bonus }
			}
		}
	}
}

As written in game/common/scripted_effects/00_decisions_effects.txt.