I have my own MK1 Laser, and it is true that it has a small slug, but the left and right offset should be correct. If we look at the photo, it seems that the square is correct, but when I put the name, it is no longer correct.
A negative number in the Line Shift column? Is that allowed?
And I would expect the required numbers to grow larger as speed increases. Something is weird there…
I have to say, the software I like the most is LightBurn, but I had to try others to rule out that my problem is software. I have done tests with Laserweb, and those offset does not appear in the edges of each letter as you can see. I don’t know what to do, since when I make a 35x10 mm rectangle, it works out well.
Turn off the scanning offset adjust, then use LightBurn to save the GCode of a small box. Run the result in an online simulator like this one: https://nraynaud.github.io/webgcode/
If it was an issue with the software, everyone would have it, not just you, so it is somehow related to your settings or your machine, but we have to figure out why.
In Laserweb, you can see how the edges of the letters come out more straight. I have deactivated the scan offset in LigthBurn. I send photos and Gcode of the 4 scans.
The only real difference in the code is that you have 12mm of overscan in LaserWeb, but only about 7.5mm in LightBurn. Try increasing the overscan amount in LightBurn by about double.