Questions regarding meditation posture and movement
I was being told that we don't practice to become experts on sitting. So if you  have intense pain, go the middle way. Acknowledge pain, acknowledge that you want to move, try to overcome the pain a bit, acknowledge unbearable, and after a few moments, if necessary, move the body mindfully (not automatically, in reaction), and carry on particing, again in still.

It is important to simply acknowledge, and even if you have to react to unbearable pain, acknowledge first, and react as if in slow motion. If you have pain and then worries about your legs, acknowledge fear (and let it go and go back to breath), if you fear mosquito, acknowledge fear etc.

If you become aware of an automatic reaction (movement) which has already taken place, acknowledge that awareness, acknowledge your thoughts about it (self-judgement, or whatever else arises) and go back to breath.

Middle way. If your meditation hall is on fire, acknowledge smelling, seeing, fear, then get up mindfully and take care of survival of yours and your fellow meditators.

I find the question you linked to be a very good explanation.