Sure, but it is not possible to honour STIB/MIVB’s numbering of floors in OSM because there are intermediary landings between the surface ("level 0") and the station hall.  Those landings will get "level –1" and the station hall becomes "level –2". (And subway/tram platforms are at –3 and –4.)

I may have a solution for this but it will require major changes to every object in the metro station, perhaps not worth the effort.  Sorry.