Here is what I think I would do with things like, pass back at U9
First, you tend to find coach shouts to gk "dont pick it up" anyway.
Leaving that aside, if there was a clear obv pass to gk, at this level, I would gauge the reaction, now, please dont think for one moment lack of appeals is ever going to influence a decision on my park, but, if keeper lifts it and there is an appeal and it is 100% a passback then, I think I would give it. You are kind of duty bound to, if its in the league rules. Afterall we dont get to pick and choose which laws to apply
However
If I feel I can "get away with it", I will, but, I will shout "keeper, mind not to use hands on passbacks", so now, everybody knows
of course, I will now have to let the other team do one too if it happens.
I am covering both applying the laws, and educating at the same there i feel.