square.onOrderCustomAttributeOwnedUpdated subscribes to order.custom_attribute.owned.updated for the selected seller. It requires ORDERS_READ.
Example
automations/square-on-order-custom-attribute-owned-updated.automation.ts
Event
A custom attribute owned by your application was created or updated for an order. The signal resolves to the officialSquare.OrderCustomAttributeOwnedUpdatedEvent payload with type narrowed to order.custom_attribute.owned.updated.