For the third puzzle, did you type the code on the table into the safe? That should have contained a note revealing the order of the real platforms.
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I did get the note eventually but until I tabbed out and back in again, I couldn't put the code in, I tried pressing E on the safe, I tried typing the numbers in manually, I tried facing each number and pressing E and nothing was working.
Knowing the right order didn't help me though when I missed the jump more than 50% of the time, too far, or not enough, at least 3 times I didn't even make it on to the first platform. I was actually considering if I could just gravestone hop it all the way, I had so many graves down there I stopped dying when I fell off because I'd land on a grave but they were too low to get back up.