Let's start with math.
I sampled all the questions marked hard.
I felt the questions were often obscurities for no valuable reason. It was as though they wanted to test reading comprehension rather than mathematics. As a dyslexic, I disapprove of this.
That said, there were no questions on the exam at any level that were more difficult than "sorta trivial". I think Khan Academy (I've watched every math video on the site as of 2021) covers every topic on the exam by 9th or 10th grade math.
Reading
Oh holy hell. I started by reading an essay... Nay... A diatribe on the importance of communicating clearly through simple wording. The author mastered the art of the 10 word run on sentence (feels as though it will never end) and perfected wording their sentences in the most technically proper but naturally uncomfortable forms. The author conveyed all their points in the first page or so and then used substantially more text to annoy the reader with absolutely unnecessary and uninteresting examples. The author should read Plato and Cicero on rhetoric as they have absolutely no knowledge of it themselves.
I can honestly say that I grew so bored of the writing that eventually started skipping a bit.
The questions were ugly. I'd like to believe I am skilled at these types of exams. But in the case of multiple choice questions, there were often intentionally ambiguous choices.... and I felt this was true for even the basic questions.
I've taken similar national exams in 5 different languages. (Norwegian, Danish, Swedish, Spanish, Italian). I faired poorly on Swedish and Italian because I understand them only due to their similarities to other languages.
The other countries had much harder math exams but that's not unusual because at least Scandinavian countries don't teach math. They teach math exam tricks to a very advanced level.
Reading exams in other countries are much better. The texts are much less pretentious and favor vocabulary common people would actually employ. Not like the author I mentioned earlier who I guess hero worshipped Chaucer.
The one notable exception I've encountered is the Norwegian B2 language exam. As someone comfortable reading university research papers written in varying degrees of Norwegian complexity the wording employed on the Norwegian B2 reading exam, a test of whether you can communicate without you peers having to change how they communicate in order to facilitate you, I encountered entire essays where I couldn't even guess what they meant. I believe this was because rather the author of those essays didn't respect the spirit or intent of the exam, a test of a person's ability to communicate and function in real world environments, they made it an academic test which tested syntax and semantics.
In summary, I wouldn't be concerned by the reading scores. I feel strongly this is a reflection upon the authors of that topic of the exam. I would be concerned by the mathematics. The exam was trivial. I've felt strongly for some time that math should be entirely self paced. Classrooms destroy mathematics. If you miss one topic you may as well just stop or retake the entire year. Teachers should focus on grading whether students learned the topic in math or if they memorized the patterns.
P.S. As a point of interest, I have evaluated many adults who scored with top grades all through school but never learned math. When a person learns math, there is no memorization involved. If you understand it, you can figure it out. "Top achievers" memorize and regurgitate. When they feel as though the information no longer holds value, they forget it.