I think for such an edit any indication of another Sith would create problems, since we have no reason to believe that Sidious has yet another apprentice hanging around, and there’s no indication (yet) that Anakin was betrayed by one of Obi-wan’s students. If I thought there was a way to suggest such betrayal in this edit the scene would probably work with a blue saber, but as it is there’s just not enough to sell that idea.

Also, I don’t think it’s worth it to establish a new location just to show the Separatist leaders being destroyed on screen, since the Jedi state that the war will end with the death of Grievous. It’s cleaner if the Separatists don’t get off Utapau.