I did skim it and it adresses all the relevant aspects. It is indeed the first hit that came up but it does show a very rigorous and scientific treatment of the topic. It is also balanced in so far as it separated out statistical measures from other valuations (to a avoid calling it "bayesian priors" which he does't claim):
Apart from reliability of change or group differences (e.g., statistical significance) and the magnitude of experimental effects (e.g., effect size or correlation), the importance of the change and the impact on client functioning add critical dimensions. Treatments that produce reliable effects may be quite different in their impact on client functioning, and clinical significance brings this issue to light.
I did skim it and it adresses all the relevant aspects
So, do show where does this particular paper tell you how to, in your words, "perform reproducible measurements".
Your quote talks about interpretation of measurements -- it says nothing about how to make sure the measurement itself is reliable and reproducible.
Sir, Could I See Your Breeding License?
Most important is that children don't have to grow up under horrible circumstances inflicted on them by the inability of their parents. You always have to weigh the freedom of some against any negative infliction it could have on others. In this case a bit less freedom would guarantee a lot less distress.
It is reasonable. I don't see how we can ask for species-appropriate animal husbandry regarding animals like chimps but not children. You have to have a drivers license for good reasons too. So why is everyone allowed to rule over helpless human beings for years without having to prove their ability to do so in a way that guarantees the well-being of their protégé?
Such discussions always remind me about something important. Children should not be assigned with any religion. There should be a certain age where they can decide what religion they want to follow, if any. This doesn't mean that religious people shouldn't be able to have children but that they shouldn't be able to force their children into a certain framework either. Parents should be forced to allow their children to take part in a educational framework based on contemporary ethics and knowledge. I don't even have a problem with lessons in religion in school as it is part of human nature. But it shall not be focused on any truth value or a certain religion but an overview and comparison with non-religious ethics and truth-seeking.