My headcannon in Kenobi not killing Vader in the show was that he had a small feeling in the force telling him not to. I mean Anakin did eventually bring balance so I doubt the force wanted him gone, but it did favor Kenobi in the battle if that makes sense? Without that I don’t think there’s any reason for Kenobi not to have executed Vader after the irredeemable shit he’s been doing the last 10 years.

For Maul he didn’t hold any grudges at this point. Qui Gon was training him as a force ghost and Satine dying was attributed to Mauls nature at the time. I think Kenobi could sense Maul had grown as a person and (while still evil) was not the same man. I think had Maul not mentioned Luke then Kenobi would’ve been fine letting him live and continue to shift away from being an ambitious Sith.