I agree that meal preparation in assisted living can be a serious issue for someone with celiac disease, especially when there are additional food allergies involved. Training, clear procedures, and consistent communication between dietary staff are very important, and repeated gluten exposures should not simply be dismissed as unavoidable mistakes.
I would add, though, that legal action is usually not the first step. It is often best to document the problems, provide written medical dietary requirements, speak with the dietary manager and facility administrator, and ask exactly what procedures are being used to prevent cross-contact. If the facility still cannot or will not provide medically appropriate meals, the resident or family can then consider escalating the matter to the long-term-care ombudsman, state licensing agency, or an attorney familiar with disability and food-allergy accommodations.
The important point is that a resident with celiac disease should not have to choose between eating unsafe food and going without an adequate meal.