Is it silly to consider whether anything you are about to do is risky?

I think I would write something that says in what way your performance is safe (e.g. that you will remain on the stage), and then elaborate a bit on what might happen during the performance and whose responsability you think it is to avoid this.
E.g. electrical safety - PA providers
kids climbing on / falling off the stage - organisers / stewards / (you?)
improperly suppervised kids - parents / organisers
fire and medical emergency - organisers / stewards / (you as the man in front of the mike?)
overcrowding and other crowd control issues - organisers / stewards / (you?)

Maybe put in a bit saying you will stop your perfomance if x,y,z, hazardous events are allowed to happen. Push the responsibilty back where it belongs.

I don't know if that is what an 'official' risk statement looks like.