Bear in mind that your HSC mark is determined by your performance on the exam. At this point, it is theoretically possible for every MX2 student in the state to score exactly 100% raw on the exam and score 50/50 for the unit. It is also stretching the laws of probability a little... after all, quantum tunnelling says that it is not impossible for my body to suddenly pass through the chair on which I am sitting, and the floor below it, and suddenly find myself downstairs, but I am even less worried about that happening than I am about catching COVID while bungee jumping off the Harbour Bridge to just reach the surface below and find that the entire harbour is filled with liquid chocolate.
Regarding your moderated assessment mark, there is nothing that you can do about assessments that have passed except to learn from them. How you could have better prepared, what areas of weakness were revealed, such considerations are useful... but obsessing about how much better you could have done if only you had a time machine and could go back and re do the test is about as productive as sleeping with a textbook under your pillow on the theory that knowledge will seep in through your ears overnight.
I know some of this may seem silly, but it is meant to highlight that focus on what you do have power to change / influence is the way forward. Use the past to guide future actions where that is useful and set aside unproductive lines of thought. This is far more easily said than done, I admit...
Good luck with it!
I'm so happy it's still possible!