I am going to offer one of those “useless” answers – sorry…
The Grid Ref you have provided is Llannefydd and was part of my old stomping ground when I was walking everywhere. I don’t recall seeing a cave there but, there again, I wasn’t looking for one either.
“Pant yr Ogof” doesn’t appear on my O/S map which wouldn’t be a surprise if it isn’t there anymore. The literal translation of the name is “Hollow Cave” or, you would know it better as “grotto”. It’s quite possible it was nothing more than that and has fallen victim to nature.
Or, perhaps, it IS there. Nearby are some well-documented caves, one of which has the prestige of being named the cave with the oldest human tooth find (or something like that).
It’s the sort of mystery that would have me out of the door in a jiffy. Sadly, I am no longer able to manage it, so I can’t go and have a look for you (sorry).
I did say it was going to be one of those “useless” answers …
Ian