Legitimate question for the peanut gallery: do Minami and Nishida know how he lost it, and if not, what DO they think happened/what’s he letting them think?
Well, based on what Nishiki says to Majima in 0, and Kashiwagi's lack of surprise at the missing eye, plenty of people definitely used to know about the whole affair back in the 80's when the story was still fresh - but since Minami and Nishida both would have joined up some time in the early 2000's, there's been nearly two whole decades by that point for the tales to get warped and retold a few times over.
I think I hc this similarly to the whole thing of Majima's not-so-missing fingers: he doesn't necessarily spread stories himself, but sometimes he'll just say vague stuff about something that happened 'way back' that has his guys forming their own speculative lore about their boss (the Majima Family is us, for real). And then he equally won't go on to correct or discredit any of the versions he hears going around, either. Overall, Majima probably doesn't really care what his people end up believing. Besides, the more stories there are going around, the less he has to acknowledge the real one.
No one would probably be brave/stupid enough to actually ask him for the real story, but if a discussion happened to be going on within earshot, I think he would definitely be one to sidle on over and do a bit of extra embellishing, adding in things he's 'also heard' - plus a little threat or two thrown in at the end; something like, "If ya really wanna know, I can get ya up front-and-center fer a real personal demonstration."
If Minami and Nishida, specifically, do know how it really happened, it would probably be because it came up some time while Saejima was also around ("Come on, kyoudai, ya mean ya ain't never told 'em? Thought this was somethin' impor'nt to ya?"); still not the entirety of the ins and outs, but at least the basics on what actually went down.