Yes,IMO Shouko didn't have the intention to report the police since the beginning. If she did, after learning Satou & Shio's hideout from Aunty, she could have lurked near Room 1208 to see with her own eyes that Shio really lived with Satou, then walked away quietly to report the cop. And to be surely safe from Satou's attack range, she could have monitored Room 1208 by a binocular from the opposite building until she saw Shio and then went to the cop. Satou would get the cop's surprise visit and have to pay for her sins without even knowing the cause of her Paradise Lost.
If Shouko cared only for Asahi, she could have reported him instead of the cop. Satou would get Asahi's surprise attack with his bat, get KOed and have Shio snatched away from her.
Shouko must know about the shutter sound of her smartphone. This means she intended to confront Satou to sincerely talk to her about Shio matter. Shouko was able to backstab Satou easily after learning from Aunty, but she didn't do it because she highly value Satou. At the time she failed to accept Satou family (Aunty) by understandable cowardice, she burst into tear apologizing Satou (who had already walked away). After that, during her conversation with Asahi, she blamed herself so much as to say she deserve to die for letting Satou down.
For me, the poor girl was stupid but her heart was in the right place.