Even if the bed shown in the photo is 290x290 the respective z joints are outside this area!
So if you have X=0 and Y=0 in the rear right corner of the bed then just measure always on the x and y axis the distance to the joints. That is what I showed you in your picture in my last post.
(For Z the x coordinate can’t be 133 if the overall bed size is 290 and the spindle is in the middle of the X axis. So this must be 290/2=145.)
If you can’t reach all corners of the bed with your hotend/BLTouch and the usable area is smaller then of course you have to adjust the points/coordinates. But then 0,0 is not in the rear right corner of the bed but a bit indented towards the center of the bed.
But as the “ball” joint is behind the bed its y coordinate must be negative!
Maybe this will help a bit although a bit confusing:
Each x or y value that points towards a Z spindle is used for the respective coordinates.
If an x value goes to the right it will be negative same for a y value that goes to the back.
Always measure parallel to the x or y axis!