If you deny miracles or if you deny that the scriptures accurately recorded the healing by faith, then there is really no discussion here.
If you maintain that the scriptures are accurate, and if you believe that God does not ordain faith healing, you are maintaining a position of cognitive dissonance.
Further, your assertion that ... that “IF” and that is a big “IF” they were truly ordained by God to perform the miracle of healing, they would never fail in their efforts. is a false strawman. The faith necessary for the healing did not come from Jesus or the Apostles, it came from the person needing to be healed. (See Mark 5)
24 A large crowd followed and pressed around him. 25And a woman was there who had been subject to bleeding for twelve years. 26She had suffered a great deal under the care of many doctors and had spent all she had, yet instead of getting better she grew worse. 27When she heard about Jesus, she came up behind him in the crowd and touched his cloak, 28because she thought, "If I just touch his clothes, I will be healed." 29Immediately her bleeding stopped and she felt in her body that she was freed from her suffering.
30At once Jesus realized that power had gone out from him. He turned around in the crowd and asked, "Who touched my clothes?"
31"You see the people crowding against you," his disciples answered, "and yet you can ask, 'Who touched me?' "
32But Jesus kept looking around to see who had done it. 33Then the woman, knowing what had happened to her, came and fell at his feet and, trembling with fear, told him the whole truth. 34He said to her, "Daughter, your faith has healed you. Go in peace and be freed from your suffering."
Lets look at verse 34 ..."YOUR faith has healed you."
Therefor it is quite possible for someone to deny in their heart that they would receive healing and thus prevent the blessing. Despite how hard the elder or healer prays it will be of no avail because the receiver of the blessing denies the blessing through their lack of faith. Even modern medicine proves out the power of faith and belief through documentation of the placebo effect.
the point is Jesus and the Apostles never failed in their miracles and they were specific and whole in their works.
Whoever this person is, he is holding himself out to be a prophet of healing and since he does not have 100% success and can repeat it over and over, then he is a charlatan and may be leading this young woman to her death.
Back when I was a physical therapist I worked with handicapped kids, mostly cerebral palsy, a few spina bifida, and a few with neurodegenerative disease. One of the saddest things in the world is hearing a child’s faith dashed by well-meaning parents who have taken him to a faith healer.
Naturally, it never changed the underlying condition and the child continued to have severe gait problems or difficulty even sitting up or holding their head erect. The child is then told their faith must not be strong enough or the Lord would have healed them.