The right footpath must be like this osm.org/edit?changeset=129681680#map=20/50.28083/4.79037. It must be at the edge (//) of the main way and not on the main way. It's this modification that I cannot do

Yes. But <Ctrl><F5> does'nt modifiy anything. I always keep the old map and I don't understand why. I did some modifications before and they were applied