Hello,

I did not create those Flixbus relations but apparently they follow the PTv2 scheme, which is an established standard for public transport in OSM.
Usually we use one node for public_transport=platform and one node for public_transport=stop_position.  They both go to the route relation.  Naming stop positions is optional, but if that is the case both nodes should have the same name.  This is correct here, the name is "Bruxelles - Brussel - Brussels" for both.
Within the stop area relation, we can add more stuff related to the bus stop: ticket vending machines, bins, shelters or the platform area itself (way 465614276).  This stuff does not go to the route relation.  The platform area should not have a name; I had deleted it in changeset 100057679.

About naming of the stops:
We usually honour the name given by the operator to its stations.  NMBS/SNCB is the railway operator of Belgium, they name the railway station "Bruxelles-Nord - Brussel-Noord" because they want to emphasize the city and in what part it is.  On the contrary, STIB/MIVB is the local operator, they never use Brussels in the name of their stops—because all of them are in Brussels—and they merely call it "Gare du Nord - Noordstation".
As for Flixbus, since they operate an international service with only one stop in Brussels, they chose to name the stop "Brussels".  So did we in OSM.  (With translations in French and Dutch because those are the official languages here.)

Hope this helps.