>>715805596Witcher mutations are extreme alterations to the whole human physiology and metabolism. They require a malleable body of a child, and even then the survival rate is well under 1/2. Adult body will just break instead of getting molded into a new shape. If she was a man, she would 100% die from this too.
But that's not even the point. The very plot point of her becoming a literal witcher is nonsensical and pointless. Considering W3's finale, it's not just magic shit, she's already stronger and more dangerous in physical combat than a mutant human, so it was just an act of completely pointless self-harm.
This decision deeks of design-by committee "make her have same attributes as previous main character so everyone will recognize and buy", I am convinced that there is no other reason.