text: Try http://www.yournavigation.org/ (set Foot as Type of transport). It works.
  GrassHopper, ORSM etc have routing problems through areas. To prevent this problem you can add an explicit highway (way) in addition to area.
  For example, look at Campo Santa Maria Formosa :https://www.openstreetmap.org/way/322882030#map=19/45.43722/12.34073&layers=N