Hi,

@HirschKauz the cave of the note is another cave not yet mapped. It is too far and I found it around the location of the note, see photo: https://drive.google.com/file/d/12FhZweUR8v9i6a12COsGPPjKvRcjxk5d

For the names of the caves already mapped:
- Keltenhiel, Sainte Barbe correspond to the source you've provided, it's the same I had used.
- But this source has a problem, Nenghis Hiel shown in the photo of the dedicated webpage http://www.speleo.lu/caves/muellerthal/nenghishiel.php is actually at the location of Kleng Barbe/Sainte Barbe.
- Location 3 Nenghis Hiel of speleo.lu looks rather like this: https://commons.wikimedia.org/wiki/File:Grotte_St_Jean_02_-_Mullerthal,_Luxembourg.jpg
This is the source I had selected for the name "Grotte Saint-Jean" in OSM because it corresponds  also with this source www.researchgate.net/figure/Formation-du-gres-de-Luxembourg-Grotte-diaclase-Saint-Jean-a-Berdorf-en-cours-de_fig2_290392356
It is possible that it has several names depending of the country, like the others caves mapped here in OSM but I didn't find any evidences confirming.

This is also why there is a fixme, the Speleo.lu source is confusing does not correspond with what's on terrain.