What she says about Soojin changes nothing that Soojin is being accused by multiple people and the accusers wont back down no matter what.
Soojin only really had 2 real accuser, the main accusers and the person who claimed that Soojin stole her jacket which was proven false because the jacket she was talking about was only released in 2019. Other people only accused Soojin of iljin behaviour not of actually bullying them, more of just being a thug to which Soojin admitted to smoking and not wearing uniform correctly but nothing else. Questions are being raised on pann about whether the stuff about her riding motorcycles was true because she wasn't notorious for it and generally those who ride motorcycles around neighbourhood would be known, but no one came out against her. Also, the main victim's sister is loosing credibility because there is inconsistency in her statements such as her mentioning that Soojin physically assaulted her sister and then later retracting that statement so its unclear whether Spojin ever did bully her sister. It's possible that Soojin may have bullied the girl, but currently there is no evidence, the sister has said she would put forward her evidence but it's been almost a month and nothing has been released and she's contradicting herself which is why unless the actual victim herself comes forward and clarifies, nothing will be clear because now its just starting to look like it was only just an argument between two girls which was spun out of proportion and because there was some truth to it, people chose to unilaterally believe the victim.