text: Ben,
  The cycle networks are mapped correcty:
  1) as there are no specifc sings "how" to cross the Vilvoorselaan, it's in my opinion logic that the functional routes "MM" and "C" cross the Vilvoordselaan via the street-level crossing
  and 2) the "Groene Wandeling" sends the cyclists via the tunnel while the pedestrians are also sent via the street-level crossing ... 
  https://www.mapillary.com/map/im/-nTod7VEOKBoy3tzIEYofw
  
  Remark concerning the bicycle (?) tunnel: it's too steep (the northern part is +/- 10%) while it is recommended to have no more than 4%, it's too narrow to cross comfortably with 2 cargo bikes and at the northern part there's  insufficient visibility 
  https://www.mapillary.com/map/im/mx9eIYVPaoug5IkCwQa1mg