The Grotte de la Font-Bargeix is not accessible to the public. It is located roughly 300m NE of the position given at the MP. It seems to be marked on the 1:25000 IGN Map. A thorough article has been linked above and still is available at: https://www.hominides.com/html/lieux/grotte-font-bargeix.php
Something is not right. This message is just to keep things from messing up down the road