This is a major cave with a GPS-verified location. However, it's odd if the nearby, officially recognized Grotte du Châtueau is located further away from the nearby Château de Saint Martin compared to this cave.

Alternative solutions:

1) Maybe replace this cave with the other, named cave? The named cave also includes links to useful metadata.

2) Or maybe, this is in fact a new (unnamed?) cave not yet previously added to OSM. Seems unlikely, but I don't know.