That brings up a potential key word there, proper. Is it possible to mess it up bad enough to leave such a scar and not kill the person? Also, while surgical procedures have become more advanced, those doing it for black market purposes may not bother with or have access to proper procedures, expertise, and tools. She could have been the victim of a middle ground procedure, with good enough tools, expertise, and procedure to keep her alive, but not enough to avoid scarring. It could also explain her odd behavioral patterns, she could have been mentally scarred and reverted to what we see in game as a result, potentially as some sort of defense mechanism. Especially if they went in with no anesthetic, I don't even want to think about that possibility, I've experienced enough WITH anesthetic as it is IRL.