Hi, im so sorry to hear about your little girl
I agree you do hear many horrible stories about shunts and malfunctioning, but a shunt malfunctioning will be no worser off than your little girl will be without having a shunt.
Without a shunt, pressure may just build and build. When a shunt malfunctions it doesnt drain off much fluid or doesnt drain of any at all, and well of course not having the VP shunt at all will be equivalent to a non functioning shunt fullstop.

Good luck, im guessing the operation has taken place by now, but just to reassure you that you have made the right decision
All the very best
Jade