Adjuster Jack gave you the applicable TX statutes re: tolling the SOL due to mental illness. The definition, below, is in layman's terms. (still not real helpful, however, is it?) Bottom line, no one here, legal pro, or other, can help your friend. She needs to seek advice from a qualified TX atty.
Did you friend seek this treatment through her HEALTH Ins? If so, she may have to go through binding Arb per her IC. The SOL is but ONE major hurdle, she will face.
She MAY have a COA against the facility for negliegence. Look up the legal defi of negligence, to understand what this all means.
The Staff had a duty to the patient to prevent harm to her, during her tx at the facility. Knowing the hx of the Pt, a prudent Staff member should have assisted her. If she was not told to wait for the Staff, or offered assistance, this could be a breach of the duty of care owed to the patient. The failure of the staff was the proximate and actual case of the Pt's injury. The Pt suffered injury due to the negligence of the Staff. (Duty, Breach, Causation, & Dams)
SOL does not run until the disability ceases (infancy – to age 18, insanity). Infants have a 10 year Statute of Repose and Statute of Limitations does not run during the absence or concealment of defendant.