If the success rate were 50%, the skeptics here and elsewhere would dismiss the results. They would say that failure rate is unacceptably high
Complete straw man and nonsense. Nobody with any ability in science would ever say that.
No, it is not a straw man. I have heard that argument from many people, including scientists who should know better. I usually ask them what they think the success rate is for cloning or generating Higgs bosons. They don't get it.