I think this Italian researcher has got something wrong.
After all, the translation 'Regarde attics aux et aux caves de roi'
seems to be someones interpretation of what is written on the Et in arcadia stone
.... (as opposed to something written in papers of the Aniorts).
However, the Peyro-Dreito stone, just up the hill from Pontils, seems to be what the 'Countess of Aniort'
was referring to, and what you could see standing by this stone (family records dating to the tenth century said that "the pierre levée des Pontils Regarde attics aux et aux caves de roi
Apparently Monsieur CROS, after talking with the villagers at RLC stll living there ?3 years after the death of Sauniere, was able to reconstruct the so called 'et in arcadia
.. ' stone. He proposed the following 'translation' - 'At Rennes, (a depot) of the King, in the caves (where is hidden) the citadelle of the Templiers'.
Another hypothesis, according to Abbe Antoine BEAUX, cure of Campagne -sur- Aude and friend of Sauniere, was 'At Rennes, in the Chapel, of the citadelle, foundation? of the Priory, for the king'
(From Franck Marie). These assertions also come from the private archives of Abbe MAZIERES.
Ahh, as i write, i have just seen the reference about the Peyro-Dreito stone (or Pontils stone, if you will):
I quote 'M. l'abbe MAZIERES nous affirma l'existence d'un document qui lui fut produit ou il etait mentionne: "La pierre levee des Pontils regarde aux greniers et aux caves du Roi'
The source for this reference is given by Franck MARIE as:
'Archives de la Maison D'a. ANIORT, A NIORT-de-SAULT'.
This is a diagram illustrating the point: