It's on layer 42 bRestrict. They used the proportional font. Disable all layers except 42 and you can see it.
I'm not sure what happens when this project is exported to CAM. I've never had to do anything with the Restrict layers before. So it either just shows up in your copper layer, or you have to do something specific to get it into the copper - probably just include it in the bottom copper when you create that Gerber.