The indirection syntax should be rewritten to be left to right.

I don't actually think so. The final answer is simply f(g(h(x))), which is a perfectly normal thing to see in programming.

That said, I still think it's a bad test. It involves no reasoning whatsoever -- merely following instructions carefully. I'm a reasonably good programmer, but sometimes a bit sloppy (that's why I write tests). So, I ended up with the correct final answer but a wrong number in one of the boxes.