“…one of the stages of Nibbana was attained without listening to a desana by an Ariya. …But they were for the higher stages of Nibbana after the Sotapanna stage(Sakadagami, Anagami, Arahant).”
This would be the case for jati Sotapannas, I figure out. (Those who are at least Sotapannas, or higher, and do not know it). That IS a question.
Metta