the barrier=kerb nodes should not go on the main sidewalk way, but rather on a "stub" connecting the main sidewalk to the crossing. From the barrier=kerb wiki page: 

https://wiki.openstreetmap.org/wiki/Tag:barrier%3Dkerb#On_a_node
> Please do not add a barrier=kerb on a node joining the footways near the crossing (e.g. sidewalk footway joining with footway crossing the road). That would implicate that such kerbs block not only crossing the road, but also just using the sidewalk (i.e. without intending to cross the road), which is almost never the case - and which has a big implication for several classes of users (most notably, wheelchair users).