Who uses a sharpie to mark their lines?

Also that looks like its used at prewire. Is there a huge issue with your boxes not being cutout by the drywallers that these are required? I have had a few boxes missed by drywallers and it may be one every 100 houses.

If you have paperwork stating where they are located they shouldn't be difficult to find. Worst case scenario you inform the builder/GC/Site Supervisor and have them sign the liability stating any drywall repair will not be paid for by your company with all labor billable at standard company rates.