I'd like to point out that when Traya killed these "three Jedi Masters" , they were in the middle of severing Meetra Surik from the Force and were, thus, distracted. I'll also point out that Traya can mask herself from detection against Force Users and Force Sensitives. A trick that didn't work on Atris' Handmaidens because they were "numb" to the Force. So, Traya didn't really kill three Jedi Masters in open combat. She, as she usually does, backstabbed them and Force Drained them while they were unprepared. A tactic that wouldn't work on Revan.
The masters were not backstabbed, they were confronted, lectured, and even with their defenses up, aware of Traya's presence, she broke right through them.
That is true, she is visible to non-force sensitives and yet she can still skulk around ever so gracefully.
But this discussion is over.