hospital/emergency department visits and sundowners (patient assault)

My LO (sister) has increasingly severe sundowners /agitation). It begins between 3-4PM and runs through the night into early morning. Boston and suburban MA hospitals know what sundowners is but are not knowledgeable or prepared to manage patients that present with it.
My sister had another UTI and kidney stone this past week that resulted in 2 ED visits.
• First visit
~ 8 hours long (arrived mid-afternoon and got a room with PureWick for extreme incontinence quickly). Results from the abdomen CT / bloodwork took long enough, but waiting for a plan took ~2.5 hours (Urology was considering admitting her for a stent). As time wore on, she became more agitated and was screaming and trying to get out of bed. Staff were pretty rough with her and I finally said I would disconnect her and "discharge" her myself if they didn't come with a resolution. Doctor came soon after, said the stone was not actually in the urethra, and discharged with a UTI prescription.

• 2nd visit – 2 days ago
Same ED, 2 days later, for the same extreme abdomen/back pain. She saw her urologist that morning, who said the stone had passed, but it was after hours and the x-ray he ordered indicated there may be another stone.

LO brought to a room quickly but the pain was bad and she was agitated. The bed did not have the front lift function to prevent her from moving forward off the bed. I told the nurse this was bad and that she'd try to move. Soon after, she was clearly agitated and they tried to give her Valium and she spit it on the floor. They said they’d give her a different medication and did not OK Valium with me first (I would not have approved due to her gait issues/leg weakness) Soon after the nurse left, my LO started screaming and moving forward and grabbed me when I tried to stop her. I screamed "HELP" loudly and nobody came. I got loose, walked out of the room, and headed to the main waiting area to get our other sister (who was not allowed back with us, saying there was a 1-person limit).

While I was gone, hospital staff (a big burly guy) repeatedly forced her down (her words; she remembered details after we returned home) and I don't know if they gave her medication (doctor told me they didn't but she was completely subdued when I returned to the room ~ 10 minutes after leaving). We can identify the staffer who abused her since he was in the main waiting area. My other sister and I talked to him about 2 of us being in our LO’s room. When he couldn’t get anyone on the phone, he went back into the ED rooms to find someone and confirm that it was okay for 2 family members to be present.

LO was injured badly injured by the staffer, with bruising on her chest, neck, and both arms. She cannot lift her left arm and cries and complains of pain when trying to get up (extreme incontinence requires frequent toilet visits). I’m taking her to urgent care for an x-ray.

My questions about this experience:
- Is this considered elderly abuse?
- Will this be considered she said/he said since I was not present to observe the abuse?
- I always discuss her dementia, sundowners, agitation during triage. Do I have any other responsibility related to this or for leaving briefly?
- This is by far the best hospital in the area (and generally our favorite; we avoid the closest one due to prior issues with medical care). If I report this, do I risk her not being allowed back?

Thanks for all feedback.