While @jbmanning5 has a point about the height, I doubt it’s going to account for all of your errors.
You can always numerically define the position by placing it accurately within the SVG. Your problem, though, will be that the tray can move. There have been a ton of discussions about precise registration using jigs, it is (to date) our best solution to the precise alignment problem. Search around and you’ll find a lot of resources.
Here’s one for jigging coasters that I wrote a while back:
https://community.glowforge.com/t/alignment-of-irregular-objects-coasters/16116?source_topic_id=18355
The matrix has a bunch of more info, including a recent addition of a jig demo video.