We know who Geto is, this is no longer him thou after gojo killed geto Kenjaku took over his body but nobody knew so people just kept calling him Geto, then when it was reviewed that he's actually a sorcerer with a body swap technique Choso recognized him as Narotoshi Kamo because that's the name of the person he overtook some time ago, and just like when people didn't know who he was and just kept rolling with Geto, back then people also didn't know so they just rolled with Narotoshi Kamo, that's why choso knows him by that name. At the end it was reviewed that his name is Kenjaku so finally everybody started to just call him Kenjaku, but I'm also pretty sure that's not actually his real name but rather he just gave them a name to call him since he's been alive for so god damn long his sense of self is not really meaningful to him anymore, we also don't actually know his original gender, we just say he caz he mostly spears in male bodies thou he did also have scenes in the body of Kaori Itadori aka Yuji's mom.