I don't belong to LinkedIn either; otherwise I would have been happy to oblige, with your permission of course. It looks as if she can be emailed or telephoned here:
https://www.immobilier.notaires.fr/fr/notaires-de-france?off... I still think it's the best option if no one here can come up with a satisfactory answer. As I said, I have contacted people out of the blue in the past on the basis of what I read from or about them on the Net and the results were quite positive. I remember contacting London solicitors who happened to have business dealings with Paris solicitors, where I found someone who knew the term I was researching in both languages. A different kind of network, but it works too.
On a different note:
matrice can mean "register" if that's any help. For instance:
matrice cadastrale
