wiki : yes

* classé  /  beschermd
* inscription sur la liste de sauvegarde / Ingeschreven op de bewaarlijst 
==> on urban brussels they also show the blue shield on their page when it's protected (it's international by unesco convention : https://www.unesco.org/fr/heritage-armed-conflicts/emblem ) and that can be spotted during survey : https://www.mapillary.com/app/?pKey=1200036975540077

The only "edge" case i see it's when a building is in "procédure de
classement" (Arrêté du Gouvernement de la Région
de Bruxelles-Capitale ) : that indicate the begin of the procédure ==> CRM <==> Ubran brussels <==>  Minister (or secretary of state) up to 2 years , strictly speaking it's not yet heritage but i can understand some user want to add this way. maybe proposed:* is better in that case.