ryans I agree we can't expect them to make custom patches for us.
I mean, it took a lot of "kicking and screaming" along with bribe money enough license revenue from the embedded device industry (think ATMs, hotel kiosks, etc) to produce builds of XP with security patches after its end of life. Can't really match that given the relative rareness of "our" issue.
What I don't think is entirely unreasonable is if we can demonstrate a consistent "cause and effect" relationship between a particular function and its impact on eyestrain that can be changed in code, perhaps certain accessibility toggles could be added. I think at a minimum we NEED to have some of our empirical research in hand to avoid sending certain engineers and project managers in a "needle in a haystack" style search which may cause hostility or lack of interest solving this.
ryans , it would be awesome to get as many details as you can on what this Vertical Blank Lock is. I'd love to see it on a capture card.
Another idea I had is while "modern" Windows probably isn't doing anything causing screen flicker by itself, a potential avenue of investigation is attempt to render the same scene by the Windows desktop/DWM on a "good" and "bad" setup and differentiate the frames between the two files.