I've run this a couple times, first with a kids' group and second with my son. In both scenarios I changed it up a little so they aren't "killing" the monsters, it's a training exercise, much like How To Train Your Dragon. They didn't kill anything, just defeated them.
In both, the kids loved it, and parents appreciated the victory without death. Many were concerned about the violence against caged creatures aspect until I told them it would be basically Pokémon rules in that nothing actually dies. With my kids' groups I always had parents present, and gave them the module to read through first.
As a GM, it's your responsibility to ensure that you change things to fit your table. It goes beyond this specific module; I don't know ANY GMs that run Curse of Strahd, for example, completely as-written.
Overall I'm very happy with this module as a great intro for young children.
[5 of 5 Stars!]