The studies that saying it causes liver damage were animal studies where they used very high doses compared to the 10-20mg dose that humans take. If you take 20 times the recommended dose of Panado you'll also end up in hospital.
Oral steroids are directly toxic to the liver due to the methyl group in the molecular structure. Damage is done when metabolising this. GW501516 is very different. It's not directly liver toxic, but it it activates and expresses genes in the liver related to a wide range of metabolic processes. This can have both positive and negative effects at the same time, and from the looks of it Scientists are still very confused about what exactly it's doing besides the obvious major effects.
If you taking GW at high enough doses and for long enough to cause liver damage, you'd be best off being more concerned about the increased risk of cancer. Anything can kill you at the right dose.