First of all, I am really pleased with your post because you deal with lots of controversial topics about education that are quite important for us as future teachers. That is, we cannot be indifferent to these questions and we must take part of these debates.
I absolutely agree with you about the changes that education has suffered, suffers and will suffer. It is true that these changes are always questioned by experts and society, in general. Besides, it is a fact, that the employed method in the educative system of any country depends on many different factors.
In relation with this, I like a lot that you show us the two faces of synthetic phonics. That is, there are experts and nations that follow these method, but there are also professionals that consider that it is not effective.
As a final conclusion, I consider that the best idea of your post is related with time. You explain us that let time take its course is the best way to know if something works correctly. Nowadays, in the university we are knowing and learning about lots of different methods and experts with different points of view, but just when we start working in schools, we will really experience the different methodologies. Then we will have a wider knowledge about the best option. Even though, we will continue with lots of doubts. Nevertheless, I suppose that the secret is not to be closed-minded to any new idea.