If it's any consolation to you, back in the days when I taught CPE classes, I used to check the answers to tests in the teacher's book before I went through them with classes, to make sure that I didn't pick the wrong answer. I was not alone. I have sat at a table with experienced native-speaking colleagues trying, not always successfully, to see why the test-setter has decided that one particular option is the only, or best, one.
I don't know about today's exams but, ten years ago, the reading and listening comprehensions seemed to be almost as much about testing a rather convoluted form of analytical intelligence as much as testing understanding of English. If they haven't changed, then my only suggestion would be to get hold of as many past tests as you can and try to see how the test setters' minds work.
Student or Learner