So I finished reading the quest, and on room A7 there are cravings depicting Akmajet leading an army of undead. It says that if a PC succeed a DC15 Society check they know the following:
Success check:
recognizes that the city is Sothis, from almost 1,000.years in the past. Behind Akmajet, several other figureslead their own lesser armies of undead. However, their faces have been chiseled out, with text written across their bodies. Written in Osiriani, the text calls the figures “ungrateful leeches” and “treacherous scum” and “unworthy of unlife.”
If I tell them that, they are going to be so confused because I couldn't find another place where they know who Akmajet is.
Where should they learn more about him?
The way I read the section, the success only lets them recognize the city as Sothis, not give them the information in the rest of the text. Akmajet is not a notable person in Golarion history as best as I can tell, just a named npc invented for this scenario. The scenario does not seem to even give the pcs a way to know his name, unless you rule they can find it written somewhere.