A couple of questions: "The liver function is well below normal" - is this based off of a pre and post Bile Acids test? If so, this is troubling. Are the liver enzymes still elevated? How much? Can you get a copy of the blood tests and post them?
"Would surgery have helped her?" What surgery? If you mean biopsy, then the answer is 'maybe'. A biopsy will not fix anything of course but might help explain the underlying cause and whether or not there are any therapies that might help. It is an important step and may provide peace of mind.
At the current time, hospitalized and supportive care needs to get her through this period. She needs to eat on her own. Is she being force fed? Feeding tube? Denamarin or denosyl and marin are helpful additions to any liver problem. Some veterinarians, myself included, like adding vitamin B to the fluids or as an injection as they can help facilitate carbohydrate metabolism and increase 'energy'. Anti-vomiting medications and injectable famotidine (pepcid) are also beneficial. Possibly some or all of these are already being used.
Finally, I am concerned regarding the existence of a mass in the presence of weight loss. This raises my concern of an aggressive malignancy.
Please let me know if there is anything else I can do. Feel free to PM me. And thanks again for the heads up RUSTYcat.