I think they're saving Maul for the Obi-Wan show or the rumored "Crimson Dawn" show starring not-Bria.
Essentially, "with age comes patience and/or wisdom" and all that. But even then he still comes off as a self-centered douchebag except when his granddaughter is involved, so its a believable old Boba.
I think its less that post-Vong ruined Boba or caused inconsistencies, and more that they flanderized his character traits (mainly conservative views, arrogance and family obsession) onto an entire culture which already had a distinct cultural identity to the point where they were all now cosplaying as him like this were the 80s, which honestly only works well in LotF where Boba is a big shot elder among them now so his influence could rub off on them, in contrast to the RC shit. In LotF at least, old Boba is still an asshole you can hate, while in Book of Boba Fett you're expected to accept that this guy has a silly heart of gold deep down.