From what I understand(someone else may want to correct me here), your current mid position has the valve not fully open. Thus, the flow is restricted and you do not get as much flow as when you push the paddle further down. When you do move the paddle further down, the valve fully opens and the line pressure is able to properly flow out of the valve.

Hopefully this will not confuse you, but here is how the pressure behaves when the pump is initiated before the valve opens:
At roughly the middle position, the 9bar flow from the pump is restricted and thus only exerts a pressure of 3 bars.

To cut the long story short, I think as long as the valve is far enough along the line such that the water can flow freely you're safe(To be fair its really not a lot of distance you need to travel for this to happen as also from the video you can see the 9 bars only requires a movement of 2-3mm on the paddle from the midpoint). What I do is simply mark the position with a sticker at which I leave the preinfusion at so I am able to repeat this shot after shot without much worry.

EDIT: With regards to moving the microswitch, you can move it but do be sure to check that you are able to move the full range of the paddle without the microswitch flexing or the paddle needle over shooting the switch which would cause some damage.