The node at the intersection of the river and the footpath is tagged as ford=stepping_stones. Additionally, the footpath segment is tagged as highway=footpath, plus again with ford=stepping_stone. I'd think it could make sense to turn the ford=stepping_stones on the path segment into surface=stepping_stones. The river seems narrow enough for the crossing itself to be mapped as node only, but wide enough for the footpath segment to reflect the stepping stones via the footpath's surface.