Wait.. So your saying that every surgery has a chance of failing because of "Pain level." I'm not sure if you are speaking for when they are awake if you are I would agree with this post.
However if you are saying there should be a "pain level" for when they are put to sleep during surgery I strongly disagree.
Yes i did get this off of google "Background. Awareness occurs when patients have anesthesia that is inadequate to keep them unconscious during an operation. ... In this situation, the patient may feelthe pain or pressure of surgery, hear conversation, experience air hunger, or have difficulty breathing."
This is the only time people feel pain during surgery is if they have inadequate anesthesia. Surgeries can fail already in the game like when I attached a rotten limb to someone he died and I had to get someone with defibrillators to bring him back.
I would say keep surgeries the same if they are on anesthesia but if they are awake add pain levels and morphine and all that.