That's a complicated mess. I think overridingly the echoes will show regret but they can distort in certain situations, so if the massacre or something related comes up that evokes that anger she'll note the darkness that creeps in. But Katie can understand murder out of sheer rage and grief for, uh... reasons, so she won't see those memories and put them together and decide Anakin is horrible. I suspect he has the potential to frighten her, but given she knows who he becomes she might just out-stubborn the fear in that whole "I am nine and I am going to singlehandedly fix everything" kind of way.

IT WILL BE A MESS. A COMPLEX ONE. We can play it by ear. :D