Also, in case, from the 1950's map, it seems that one of the path you surveyed continued at that time even further along Ruisseau de la Gorge ; maybe it's worth exploring it
https://www.geoportail.gouv.fr/carte?c=6.0095561857303075,44.888440057736545&z=16&l0=ORTHOIMAGERY.ORTHOPHOTOS::GEOPORTAIL:OGC:WMTS(1;h)&l1=GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN25TOUR.CV::GEOPORTAIL:OGC:WMTS(1;h)&l2=GEOGRAPHICALGRIDSYSTEMS.MAPS.SCAN50.1950::GEOPORTAIL:OGC:WMTS(1)&l3=GEOGRAPHICALGRIDSYSTEMS.SLOPES.MOUNTAIN::GEOPORTAIL:OGC:WMTS(0;h)&l4=IGNF_LIDAR-HD_MNT_ELEVATION.ELEVATIONGRIDCOVERAGE.SHADOW(0;h)&l5=OPEN_STREET_MAP::GEOPORTAIL:OGC:WMTS(0;h)&permalink=yes