Hi Florence,
First, the remark, "that the further east one travels, the more Chinese the architecture becomes...etc," was not miy comment, but part of Gunner Mikkelsen's introduction to Lyndon's talk.
Second, in my recollections (possibly influenced by other conversations with Lyndon) he was focused on what was actually recovered at any site. From that perspective, his conclusions would have been 'evidence based.'
Thirdly, regarding the extent of Chinese cultural influence (including building techniques), Chinese cultural influence extended to areas outside Chinese political influence (e.g. Japan, Korea, and Vietnam and the so-called Northern dynasties). A similar process occurs in the contemporary world, where the cultural influence of the USA (for better or worse) extends far beyond the political boundaries of the USA. (With American troops based in some 75 other nations and 900 odd overseas bases it has become somewhat difficult to define even political boundaries.) The cultural influences can be observed everywhere.
Finally, I've always found Lyndon approachable. While he's likely a busy guy (family (new), work, sport (cricket) and archaeologically) I'm sure he would at least offer brief comments on your questions.
I might add that Gunner Mikkelson has a deep interest and knowledge concerning Manicheanism. He is still on MU staff and you will find his email address in MU's A.H. staff list.
For myself, I retain A.H.interests, mainly centred on the Asian interconnection of knowledge, and when I graduate will have (by accident) a major in A.H. and a minor in Japanese studies. But my academic interests lie more in contemporary events in Asia, focusing on the amazing re-organisation of The People's Republic of China. Historians seldom live through the reality of such a sea change in political power.
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Other Points.
1. Are you aware of what is sometimes described as the 'last' Manichean temple in the world, located in the city of Quanzhou, Fujian Province, PRC. I've tried twice to visit it, but there were floods in the south, so I did not try. The building has been renovated, and I believe it is in an ornate Chinese style. That work was done quite a while ago and I think indicates some official's viewpoint. Contemporary Chinese archaeologists are now very professional, so I have hope that one day the city will renovate in a much more historically sympathetic style. The building is currently used by Buddhists (or so I understand).

Quanzhou also has a good Maritime museum as Quanzhou was once a busy trading port.
Macquarie U, staff have visited the temple and you can read of it at:
http://www.mq.edu.au/research/research-centres-groups-and-facilities/resilient-societies/centres/ancient-cultures-research-centre/research/research-projects/manichaean-and-nestorian-christian-remains-in-zayton
There is also a good academic book (2011) on the remains, a review can be found at:
https://www.cambridge.org/core/journals/journal-of-the-royal-asiatic-society/article/div-classtitlemedieval-christian-and-manichaean-remains-from-quanzhou-zayton-corpus-fontium-manichaeorum-series-archaeologica-et-iconographica-by-samuel-n-clieu-lanceeccles-majellafranzmann-iaingardner-and-kenparry-pp-x-282-turnhout-brepols-2012div/D7DF67CFAC310B02CA9AA4CAE4737B37
I think overall, we can see the Manicheans (despite some weird ideas) as a rather dynamic group that "filled the world" with their preaching, and gave more orthodox Christians a run for their money (grin).