Congrats on recovering it.
Personally, I'd turn the thief in -- letting him get away with it just encourages him go steal someone else's IMHO, and next time perhaps he'll research how you found yours and know to wipe the things or at least turn off iCloud/findmyphone. I assume we're not talking about an impulsive 6 year old but someone who knows he was stealing something valuable. Whether the school gives a warning or imposes real consequences is up to them, I just would have ensured they were aware of the theft.
Personally, I'd turn the thief in -- letting him get away with it just encourages him go steal someone else's IMHO, and next time perhaps he'll research how you found yours and know to wipe the things or at least turn off iCloud/findmyphone. I assume we're not talking about an impulsive 6 year old but someone who knows he was stealing something valuable. Whether the school gives a warning or imposes real consequences is up to them, I just would have ensured they were aware of the theft.