I actually had a crack at a good day for a change.
So first up was completing the nail hole plugging, and being a good Boy Scout testing if it was good for a knot as well

10 mm prep drill for the door nail holes and a 10mm plug cutter for donor material

The knot was too big for any of my plug cutters so I used hole saws minus the pilot drill

It all seemed to work well

a little glue and tap tap tap

not exactly invisible but a satisfactory first  attempt

moving right along it was time for the "trick up my sleeve"

Many years ago I used to make maps of Australia out of MDF for craft fairs using a 3 mm straight cut  router bit.

This I brought out of its slumber to work again on the credenza doors  profiles,
setting everything up I did a test cut on the frame.

Only to find it burnt the timber so I decided to use a spiral upcut solid tungsten one.

That produced a far better  result even with the whiskers
I started  on the fixed panel door with the square pattern.

Reset the jig and continued

finishing with the desired effect.

Reset the jig again for a 45 Deg pattern

Finishing with  the desired effect again.

Being impressed with myself,  and BTW I did break a couple of bits on the way.

I brought out my faithful companion Guinevere to do the best whisker shave job going.

a excellent finish.

Now for the dilemma of finding Face Frame Inset euro hinges, as it appears Face Frames are lesser used in modern furniture  in preference for Space saving Frameless.