"Does the stimulation help the brain plastercise? Or simply slow down the healing process?
I read so much conflicting information, it's like nobody has any clue what they're talking about. "

The brain heals best during non-symptomatic periods. I don't understand the plastercise question. What conflicting info are you finding ?

Have you tried to teach the kids to be less noisy ? Noise is not a necessary part of being a kid. I believe kids are conditioned to expect life to be loud and rambunctious. I was one of 6 kids in a 3 bedroom house. My wife and I raised 3 kids without over-stimulating noise. Noise is for outside (outside voices). A less stimulating environment is possible. Maybe you can find a medium level that is tolerable.