I don’t claim to know the intricacies of this problem but it seems directionally correct to have such a thing rather than not.
The goal shouldn’t be to necessarily punish kids but to better identify issues and rehabilitate kids. The school systems are currently turning a blind eye and letting problems fester and compound. That is not the way to go.
From what I understand, there are legal implications for teachers who intervene and this prevents them from doing anything even if they wanted to. We can definitely do better.
Because that's actually hard, and requires a culture change. Much easier to simply add extra regulations (that criminals will ignore) for the average law abiding citizen and get reelected claiming you "did something".
Why are kids plotting mass shootings? It's not because they have access to weapons. It's because something is VERY broken in their family nucleus and values.
I understand your point that there's no way the government can police family education. But what I would suggest is to make parents and legal guardians directly and fully responsible for their kids crimes.
Your children killed? You are charged with accessory murder or manslaughter. Your daughter stole? YOU are charged as well.
It is YOUR choice what you decide to teach or not to your kids. But on the flipside, it also becomes your responsibility.
This would also work with the problems the UK had (I lived there several years ago) of delinquent kids. You had 10 year olds doing crime who just got ASBOs (collectable paper for them,) and the parents were nowhere to be seen. Charge the parents for their children crimes, as adults.
People have repeatedly called out online hate speech as a contributory factor in mass shootings, and that runs into first amendment problems.