These are going to be a nightmare from hell to re-work on a number of fronts:
First, you’re going to have to fixture them and locate the existing features.
Then you’re going to have to find the ones that are too small…the photo’s not very good, but they look all over the place to me, in size, in geometry and in location.
Next you’re going to have to figure out how to interpolate them bigger with an 0.005″ diamond pin…plan to spend a lot of money on pins and good luck sourcing them; the smallest I could find with a quick Google search is 0.015″
I don’t think you’re going to mill them with carbide…sintered alumina is harder than a woodpecker’s lips.
If, by chance, you think they can be re-worked with laser, your problem is all about fixturing.
I’d dope slap my brother for blithely getting you into this mess, then I’d sit down with the customer and have a realistic conversation about reworking them vs tossing them in the scrapper and beginning again.
If these are cut with a laser from a large sheet, they can just lay the sheet down and put in all the holes, then walk around the outline faster than you can even handle the tiny bits to get them in the jig.
Sometimes, painful as it is, you just have to recognize when to run away screaming!
On edit: You just might, with a LOT of patience, be able to hand lap them out with diamond coated wire like the kind used for precision wire sawing.
It goes down to 0.1mm.
However, you have 1800 holes to do under the microscope.
You’ll be a gibbering loon long before the job is done, so if you commit to trying this CHARGE LOTS!