At the very least they should do some form of community service. Or they should have a criminal record. As it is, they've got away with it
*Gone2far - They have got a criminal record and will be doing community service. They have very definitely not got away with it.
They pleaded guilty to criminal damage. They have been given 12 month referral orders. That is a community sentence and is the one most commonly used for offenders aged 10-17. The maximum length of a referral order is 12 months. It means they will have to agree and comply with a contract of rehabilitative and restorative elements. This may include reparation or restitution to the victims in addition to the compensation the parents have been ordered to pay.
There was a fourth boy involved who will be sentenced next month. It isn't clear why his sentencing has been delayed.
As the article mentions, over £100,000 has been raised to help pay for the damage. Unfortunately, no amount of money can compensate fully. A model that has been built from scratch by the modeller over 20+ years can never be fully replaced.