Provided the prosecution doesn't negotiate the charge to become 'affray' which here in the UK holds a higher tariff, based only upon what I've assimilated from what has been written, it would be my thought to accept a plea. Insofar as age is concerned, I have every confidence this would not remain a blot on a life's record. There may...and only 'may' be a brief custodial sentence, which the judge might issue in the belief that they could receive much needed counselling - this, in its entirety is not a bad thing although I can understand from the perpetrator's perspective sounds grim, but it allows distancing, reflection, and repair. However, in the absence of this I am equally confident there will be a firm placement of a community service, combined with supervised probation.
I wish you every success in your endeavours.
FT