In lieu of an answer, this question has been answered a few times by deleted accounts 1, 2, 3 which give you some brief answers to this question. Active users such as u/Viet_Conga_Line touched on the subject of the cult's antiquity in archeology in an answer here, and if you're interested in some answers about Roman mystery religions in general there's a discussion here by u/tsddam and u/Tiako.