Hi,
You've been busy.
Are you using a Hall effect device for your end stop sensor? Interesting.
As to my sensors keep in mind they they are IR beam break devices. They are attached to the frame. On the moving part (be it X,Y,Z) there is a printed part that moves into place and breaks the beam.
Since these is nothing about the sensor that prohibits further movement the moving part can continue past the point where the sensor is first activated, assuming nothing else gets in the way.
Since the point of these sensors is to determine that the moving part has reached a certain position there is no real requirement that the sensor activate at the extreme end of travel or at the min or max axis position.
My sensors activate some 10 mm away from the min end of each axis. It is a simple matter to determine what the actual position is. So rather than adjust sensor position to yield a specific axis position I set the axis position using G92 to the actual position.
The result is the same using either approach, the firmware now knows where the moving part is.
As to accuracy I have taken no measurements. It is good enough to allow pausing and resuming a print. If that is not of concern it doesn't really matter if the X or Y position is off a mm or two at the start of a print.
As to the Z position I use a BLTouch probe to set the Z=0 datum independent of the Z end stop sensor. The Z end stop sensor gets the bed where it needs to be for homing purposes. The probe determines where it actually is for printing purposes.
Frederick