When people say don't use age as an excuse, you need to realize that each person is different. 12 year old can be the most educated while another 12 year old would be more childish.
I've been called names when I was young, but I know my bullies were kids and made a mistake. I can forgive and be happy if they end up being successful.
I won't say it didn't leave a mark on me as an adult - I have social anxiety but sometimes you pay for someone else's mistake.
Life isn't fair. that's a fact. but blaming them for being immature for the rest of their lives isn't fair either, especially if they regret it deeply.
Plus, if the victim has forgiven Taeyong, I don't think we have any right to say anything about this case.