I just did a little rereading and the info we have thus far confirms some stuff and makes some other things possible.
The Pantheon that Aurelion Sol killed in Twin Dawns was Astraea. She had Areion's spear - we can assume Areion immediately preceded her as Pantheon - and her own cloak of stars, *but no shield is mentioned,* so ostensibly no Zeonia yet. Twin Dawns notes the next Pantheon after Astraea being male, so it's possible that the story could need some edits but also there could just have been a really unremarkable Pantheon after her.
The golden-armored, flame-haired warrior queen who sealed the darkin, either presumed or confirmed to be another previous Pantheon, might be Zeonia, the original wielder of the Aegis. (Well... I was *told* a while back that the queen was a previous Pantheon by a secondhand source... But that might've changed.)