get_artifact_quality_effect

get_artifact_quality_effect = {
	if = {
		limit = {
			NOT = { exists = scope:quality }
		}
		# Some random variance is added so artifact quality isn't completely deterministic
		if = {
			limit = {
				NOR = {
					exists = scope:inspiration_owner
					exists = scope:random_quality_bonus
				}
			}
			random_list = {
				20 = {
					save_scope_value_as = {
						name = random_quality_bonus
						value = 4
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_quality_bonus
						value = 8
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_quality_bonus
						value = 12
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_quality_bonus
						value = 16
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_quality_bonus
						value = 20
					}
				}
			}
		}
		else_if = {
			limit = {
				NOT = { exists = scope:random_inspired_skill_quality_bonus }
			}
			random_list = {
				20 = {
					save_scope_value_as = {
						name = random_inspired_skill_quality_bonus
						value = 0.5
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_inspired_skill_quality_bonus
						value = 1
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_inspired_skill_quality_bonus
						value = 2
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_inspired_skill_quality_bonus
						value = 2.5
					}
				}
				20 = {
					save_scope_value_as = {
						name = random_inspired_skill_quality_bonus
						value = 3
					}
				}
			}
			save_scope_value_as = {
				name = random_quality_bonus
				value = 0
			}
		}

		# Calculate the final quality of the artifact
		save_scope_value_as = {
			name = quality
			value = {
				value = scope:random_quality_bonus
				
				# Cultural tradition for piety level boosting artifacts
				if = {
					limit = {
						court_owner.culture ?= {
							has_cultural_parameter = piety_level_affect_artifact_quality
						}
					}
					add = {
						value = court_owner.piety_level
						multiply = 5
					}
				}

				# Bonus Quality from the Court Owner's Amenities
				if = {
					limit = {
						court_owner ?= {
							has_royal_court = yes
							has_dlc_feature = royal_court
							amenity_level = { target = court_lodging_standards value > low_amenity_level }
						}
					}
					if = {
						limit = { court_owner = { amenity_level = { target = court_lodging_standards value >= max_amenity_level } } }
						add = 10
					}

As written in game/common/scripted_effects/00_ep1_artifact_creation_effects.txt.