Engraving front to back is the default, because most machines vent in the rear, and this keeps smoke from sticking to the parts that have just been freshly engraved.
If you don’t have the machine sizes or steps set up properly, the camera simply won’t work for you - it depends on being able to send the laser to “real” physical positions with accuracy. Get the machine set up and tuned properly first, then set up the camera and you should have much better luck.
There are a couple things that could contribute to the issues you’re having:
- Machine size (sounds like you got this set up now)
- Step size calibration (could also be an issue)
For step calibration, read here: How are steps calibrated?