Ishita should have allowed Pihu to go back into the boarding school as the girl can atleast breathe there. Her purpose of getting Pihu to the office was done which was knowing her whereabouts. From here she should have taken the judicial way to meet Pihu rather than making her stay in Bhalla house which is more torturing.
CV's have taken a very serious issue once again which is Chile abuse. This track was taken up during 1st leap also and now once again. In the first track it was indeed handled well but here since they are showing the abuse done by aunt itself, CV's have to be careful with the ending as Ektas logic of family comes first and forgiving in family should be there cannot be implied here. she needs to be punished harshly and as you said her character needs to end after this track as their is no scope of redemption or acceprance of this character anymore.
Secondly, CV's should show Pihu gathering her courage and opening her mouth to stop grievances coz the strength of any abuser is the abused silence. Through this the CV's should pass out a strong message that the abused child should speak up about their problem with their near and dear ones , however scared they are.
Thirdly, CV's in order to show Ishita as a problem solver should not allow her to keep hiding this fact from people. She should be sharing about this problem and asking help from people like Adi, Ruhi, Aaliyah, Romi and Mihika who have shown after leap that they are with her in her plans.
Ishita should also be shown taking drastic steps such as installing CCTV in Pihu 's room and exposing Simmi's face in front of all by playing that video.
I hope the way CV's handled the first child abuse track, they handle even this properly.