The changeset was probably not useful at all and I had warned the user (https://www.openstreetmap.org/changeset/136360776) that those kerbs are probably not useful at all—unless we draw some footways across the area.  So it was a micromapping exercice for nothing.  And wrong, by the way.

I don’t know a good tag for inclined kerbs (kerb:incline is apparently if the inclination is facing the user, not for cases where it differs between the two end points) but to improve it the best way is probably to split each kerb in two parts, one having kerb=raised and the other kerb=lowered (or flush if that is perfectly level).