What will happen if this user now apologize and and repay the loan , will Negative change to neutrel (asking just for learning purpose)?
Yeah, why not?
As far as I can see the negative feedback he got because of defaulting loan, not because of cheating in a same campaign. If he have joined in a same campaign, then it's definitely deserve negative feedback and there's no way to forgive him.
There's no rule about how many alt accounts someone can create, so it's technically fair.