The whole issue gets convoluted. The 2 witness rule isn't the problem as much as the fact that unqualified people are handling criminal matters. That is the main problem as I see it. Why are elders handling crimes against children in the first place? Why do parents go to them first? Why isn't the policy of the JWs as simple as report it to the proper authorities (hint: that's not the eldurrs)? They have no business handling it in the first place.
Now, since they do, and since they set themselves on high as the judge and jury of the congregation, then the two witness rule allows horrible things to go unpunished and allows predators to do what they do even longer. You'd think an almighty god that can cause the rocks to cry out with his message could do so in defense of the most vulnerable among us. That's just more evidence that god is a fairy tale. He can be found helping to protect his loyal witnesses across waters where predators roam so they can get to a meeting while children are raped because, of course, meeting attendance is vital. Disgusting.