CNC not square (Followup on inlay problem)

CNC Machines Shapeoko 5 Pro
1

In my followup on my Inlay process not going right, I decided to do some testing on my CNC. I carved a 200 mm by 200 mm square in a piece of wood.
I was happy to mesure 200 by 200 for the result piece

I am sad to see that it is not square. I checked the square of my machine and from 1 corner to the other, I mesured 41.5 and from the 2 opposite corner, I mesured 41.25.

1- Do you think is what is affecting the result of my square piece of wood not being “square”?
2- Do you think this is what is affecting my “not aligned” result of the male piece in my female piece of my “Inlays”???

And do you have “tips” on how I can correct this?

2

The diagonal measurement of the machine doesn’t matter at all; the only thing that matters is that the two Y rails are parallel. If they’re not, the machine will bind.

“Square”, or the angle between the X axis and the Y, is set by the two Y homing switches on the Shapeoko 5 Pro.