Yes, the act of lying, in itself, does not make one guilty of murder.
It is the context of the lies that can tell a story, imo. In this case, the lies she told to the victims had an explicit purpose, according to her. She told us that she told the lies about having upcoming cancer treatments because she needed childcare help in the future because she had bariatric surgery scheduled. That is the context of the lies according to the defense.
If that^^^ had been true, then maybe some would accept it and sympathise with her----and it could add to possibility she was innocent, and the lies about cancer were successfully explained by her bariatric upcoming surgery.
HOWEVER, when it was revealed that there was no bariatric surgery scheduled and there never was, and all that was just more lies by her, piled up on the others---then more questions arise.
And the context of those lies then create a new narrative. It is no longer 'lies created to help her get childcare for upcoming surgery.'
Now it can possibly revert back to the original allegations by the prosecution---->>that the lies were told in order to lure 4 people to a luncheon at her home, where they were served death caps.