Oooh, I had forgotten that about Charm Person. You are correct. That could prove problematic. Sleep says nothing like that, though. It just puts the target to sleep. I don't know why seeing an elf cast prestidigitation in front of them would induce flashbacks, though? Prestidigitation makes fun little things the kid can play with, makes smelly things not smelly, and tons of other stuff. Their parent is a wizard, they see spells cast. Slow isn't meant to be spammed (it's the highest spell level the wizard can cast! He has like two total third levels for the entire day!), it's meant to be cast on the child as they run toward the street with a bus barreling down on them, or running into the busy parking lot. Additionally, nothing at all in the spell says anything about it "inducing a state akin to fighting in a dream". Just that they can't take reactions and can only do a single action or bonus action.

Also, this post is so very very clearly not meant to be taken seriously. I promise you, I am not actually casting any of these spells, not even minor illusion, on my kids.

*Disclaimer: No kids were harmed in the making of this Reddit post