regarding the matriarch's predecessor: what information about them is available? i.e. what sort of ruler were they, etc.

(sorry, just saw the answer regarding how this matriarch came into power!)

forgot to add that sylvia would've been looking in the library, but if there are any other ways (i.e. hearsay) that this info would be available for the mirrorbound then i'd like to know those too! thank you!