See https://wiki.openstreetmap.org/wiki/WikiProject_Belgium/Building_and_address_import (this is the Wallonia part).

Technically the import procedure for Wallonia hasn't been followed yet but, since it's just the same as the Flemish import, there is informal consensus on this within Belgium (or within the OSM.be local chapter's community channels at least). Several mappers have introduced thousands of buildings and addresses using this tool in the last 2 years, with no-one complaining up till now as far as I'm aware. I suppose it slipped our collective mind to complete the procedure. We're making plans to work on that now.

In the OSM.be chat, Le_Sharkoïste asked for help dealing with this matter, which is very sternly worded indeed. They report not remembering any past warnings, and I don't see any public warnings either (at least leaving a changeset comment is usual for this kind of matter), were those sent via PM?