sculpture_improvement_effect

sculpture_improvement_effect = {
	random_list = {
		10 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_monthly_prestige_1_modifier }
		}
		10 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_court_grandeur_baseline_add_1_modifier }
		}
		10 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_monthly_piety_1_modifier }
		}
		10 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_monthly_prestige_add_1_modifier }
		}
		10 = {
			trigger = { 
				artifact_owner.top_overlord ?= {
					NOT = { government_has_flag = no_powerful_vassals }
				}
			}
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_happy_powerful_vassal_tax_contribution_mult_1_modifier }
		}
		10 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_courtly_tax_contribution_mult_1_modifier }
		}
		2 = {
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_courtly_vassal_opinion_1_modifier }
		}
		10 = {
			trigger = {
				scope:liege = { NOT = { government_has_flag = government_is_nomadic } } 
			}
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_development_growth_1_modifier }
		}
		10 = {
			trigger = {
				scope:liege = { government_has_flag = government_is_nomadic } 
			}
			antiquarian_apply_modifier_to_artifact_effect = { MODIFIER = artifact_fertility_growth_1_modifier }
		}
	}
}

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