Ok, I'm glad you are happily back together but let's get to the bottom of this so you aren't having to check the valves so often.
1.)first 21k went without problem... (Got that, I asked when the valves were adjusted before that.)
2.)the valve in the picture in the beginning is coated in a heavy varnish and the varnish is pitted...and indeed stopped sealing... it was not reused (So the valve is not pitted, the varnish is?)
3.)timing is spot on. I use the ducati tool for setting the cams and a degree wheel. (That's cam timing. Have you verified ignition timing?) That would be the most likely source of odd combustion issues. Even systems that adjust electronically must have a relative sensor position.
4.)rides are full of corners so I'm heavy on the throttle: https://youtu.be/Q-QmtG-vF28
(I guess that means you don't ride around at 8K when you are going 30 mph cruise. That can cause you to be in a mapping area that is not properly mapped.(run hotter) I don't know what your bike has but a closed loop cruising operation can be turned off at high rpms.)
5.)ecu code presented on the dash is ERR ENG. (That's a dash display, not the error. Do you have a code reader or can you take it to a dealer next time you have an error to see which sensor is reading what?)
When you say you shimmed to the "tightest" allowable settings, I am going to assume you are not just adjusting them to the low end of the range because that would put you right next to being out of range as I explained previously.
Maybe you are tired of discussing it but I am willing to see you through it if you want. If not, that;s cool. If I had to inspect valves every 2K miles, I would probably never touch a Ducati again. To do the job correctly, means that it is perfectly repeatable (re-measure) immediately after adjusting them and turning the engine over a few rotations. Secondly, you have to actually be adjusting them to the correct values and while it sounds simple, it took me half a lifetime to learn to adjust valves with feeler gauges and I am not sure I am done learning. For example, I went to a club garage session a month ago and a friend of mine for 45 years did something I have never seen before. Besides that, I might have been the only person there that understood his explanation.