Author: The term is 'overengineering.' You used thick wood and heavy bolts to compensate for the stresses placed on a structure which gives exceptional amounts of leverage on the joints. Overengineering isn't good engineering.
This thing is a nice first prototype, but it looks like a death trap. There is absolutely no reason for the giant lever arm coming up from behind you and all the way around.
Look at the altwork design. It's a lot lighter and more robust. It doesn't place a ton of weight overhead, and there's a lot less leverage on the joints. Or look at ErgoQuest. The monitors are stationary, and only a lightweight desk/keyboard tray moves.
I appreciate your confidence, but I'm afraid it's misplaced. I've been doing woodworking and engineering for a lot more than 15 years. A couple of things to consider:
"When you want to build this kind of structure, I'm not sure you can plan everything beforehand, there are always things that will happen that you didn't expect." You absolutely can. It just takes practice and experience. When I build something, I plan out what I do, and 9/10 it comes together on the first go. For my mentors, it's 10/10. The first few years I was doing this, it was 0/10.
"After a few failing choices, I ended up with a main pole of 7cm x 7cm." You generally want about a 10x safety margin for dynamic loading and similar issues. If you had a few failing designs, you're way too close to failing in your current design.
Back to the overengineering point: Simply using massive beams of wood and bolts doesn't necessarily make things robust. A 7cm x 7cm piece of wood weighs a ton, and puts that much more strain on everything. That's true for all the pieces. I could build a more robust design with normal-sized boards. That has the distinct advantage that if there is a failure, what falls on me my hurt me, but won't kill or cripple me.
I'm glad you're trying, but by overestimating your expertise, you're putting yourself at risk. I'd encourage you to keep trying, but to also take this sort of constructive criticism seriously.
Think through how the desk ought to move so you don't need the giant lever arm, whether you want the monitors to move at all, and where to mount these so you can get in and out easily. I can think of a half-dozen designs where there are no massive lever arms, where nothing moves or just the keyboard tray moves, where if things break, I don't die, and generally simpler, lighter, and more robust.