Punished? As is agency diciplines them. No. Criminal charges for the entire bunch.
Tis why I said "assuming no criminal charges".
It was a training failure from the looks of the video. If they were subject to normal criminal proceedings and didn't have qualified immunity, they'd be charged with Involuntary manslaughter as there was no malice aforethought (ie they weren't trying to kill the guy, as opposed to killing the guy in the heat of the moment or a fit of rage). Specifically, criminally negligent manslaughter. "omission to act when there is a duty to do so, or a failure to perform a duty owed, which leads to a death."
For the military, if you are detaining a person, you have a duty to ensure the welfare of said detainee ABOVE YOUR OWN SELF. So, if you cuff or hogtie or even sit on a person, and they suffocate to death, you committed criminally negligent manslaughter. I know civilian police are given substantial leeway, but I sincerely doubt the courts have ruled that the police have no duty to act when it comes to saving the life of a person they have detained.
Qualified immunity is a tough nut to crack. Most folks don't try. Suing the department on the other hand, while less satisfying, is substantially easier. So, yes, likely she will get a settlement from the department's insurance company. Said insurance company will be the stick that drives the reform by demanding that said department has adequate training on (amongst other things) how to detain a person without killing them. IMHO, that's probably the largest driver of training improvement of American police departments. Losing lawsuits, and insurance companies demanding SOP changes to save money on future settlements.
It's a bad system, but it's the only common one we have. The other measures (politically imposed moderation, civilian review boards, 'reform', etc) are sporadic at best.