I think the big secret you let out was he prints first, then machines, drills, and routes the printed playfields, with a two step CC application... his problem more than likely is the fact the ink on the printed wood, without that initial CC is so delicate and easy to damage in the handling process, the intermediate CC is there to protect the artwork during the machining phase. That a second CC is then added on top of this only adds to the problems. I suspect that speed of production and cure times are involved in some way, and that the vibration due to machining is possibly stressing the ink bond at machined edges due to cutting the harder CC... but this is all just conjecture. I can think of a simple battery of tests that would determine what is causing the issue, but they may already know what is causing it, and production schedules will just not allow them to change the process.