Sadly you're probably right, the kids will likely not be severely punished (as far as civil or criminal law is concerned) now what their parents may do !!!!!!!!!!!!!!!
OPINION: The barn owners insurance company could seek civil damages against the persons who committed arson and to what extent (if any) the law holds their parents liable. I doubt (but cant possibly know NOT having read their insurance contract) the parents have insurance to cover the civil torts of their children such as arson and to replace the structure their kids torched. If the child burned the parents home down their own home loss may be covered (absent perhaps any exceptions if a family member committed arson) but if their children burn down another persons barn, the parents homeowners insurance on their house may NOT cover another structure (own home is insured but likely NOT other property), especially if the other structure is intentionally burned down.
NOTE AND DISCLAIMER Insurance law is a matter of strict contract interpretation and NOT by what myself an attorney or any other person thinks is right or fair (makes no difference) ITS "PRIMARILY" WHAT THE CONTRACT SAYS THAT MATTERS AND IS ENFORCEABLE. I have NOT read the insurance contract nor researched the laws of the state where the damage occurred, so whether or not the parents may be held liable for the torts of their children or whether the parents have any kind of insurance that covers a structure their kids burn down I DO NOT KNOW NOR CAN ANYONE KNOW NOT HAVING READ THE INSURANCE CONTRACT (or what they think is fair or their own contract says)
SO NO WARRANTY GET IT LOL
John T Country Lawyer