I've gone over Witness 18 statements and interviews and have come to the conclusion she hasn't necessarily been contradictory, she just doesn't have much to add to the body of evidence.
She says she was looking out her window and saw two people struggling on the ground, actually grass. She can't identify them, all she can say is the "larger" man was on top. From a witness standpoint this is pretty useless as 6'3" TM in a large, baggy hoodie could appear to be the larger man on top. She hears a gunshot.
She says she went to get her phone, which would concur with her statements she was in bed reading a book in her nightie...nobody carries their phone with them when they go to bed. She then walks back to the window and sees Z getting off of TM as she calls 911.
The time it would take for her to retrieve her phone and get back to the window would allow Z the time to roll TM over and get on top of him, as he states.
One item of note, she DOES say when she heard the sound they were on the grass, which is consistent with Z's statement that he maneuvered over to the grass to minimize damage to his head.
I see very little of use in her testimony to either the pross or def. Her statements might be entered as evidence but I doubt she will be called as a witness. She has little substantive to add.
Check that, she will have something substantive to add...for the defense. She will be able conclusively show via her eyewitness testimony that both men were on the ground, one on top of the other, when the shot was fired.
Everything she says seems to corroborate Z's version...at least at that moment.