these performances are great.  what are you using for your MIDI board?  the level of control and subtlety is awesome.  even if i could play like this i couldn't get it out of my MIDI board ...

The following video shows a glimpse of my way of tackling musical expressions.
In the video, I draw the controller data by mouse.
But I use the Modulation wheel to input(record) controller data, usually in real-time.

https://youtu.be/XdnpQgXwkQM

I realized that it must not be based on a 440 A, or it must be playing along in quarter tones (I remember reading a story that the composers were thrown in jail during the cultural revolution, but couldn't remember if it was because the influences were traditional, the instruments were contemporary, or some hybrid of the two 'problems' seen as sins by the administration at that time).

It is based on 440A, but the temperament is different....somewhat like the meantone, but not exactly. But I use Zarlino temperament and 432A in my recording.

In the cultural revolution, if you have a piano or violin, you were seen as a sin.
A crazy world.

I enjoyed it very much.  Reminded me of one of my favorites, the "Butterfly Lover's Concerto", by Zhanhao and Gang.

Yeah, the forever Butterfly Lovers
https://youtu.be/mbaPSKlIbkw

but to me the 'ErHu' sounds more like a viola! What were the other instruments?

I check the original file. Oh, I just make a mistake.
You are right, It isn't ErHu, it is a violin.

Other instruments are:
Guitar, GuQin, Sitar, Piano, Cello

I have used virtual ErHu in this video

https://youtu.be/vhKAJKBNkhE

This is lovely, but to me the 'ErHu' sounds more like a viola! What were the other instruments?

https://youtu.be/vhKAJKBNkhE

Very enjoyable, with the virtual violin standing in nicely for the ErHu. I don't suppose there is such a thing as a modelled ErHu, but there ought to be!

There are modeled ErHu, I have more than one of them.
But for this piece, the Violin is better.
However, I had altered the string tension of the violin, making it sounds not so "Violin".
That modeled ErHu I own sounds good, but are not capable of playing this complex piece.
They have a limited range of useful notes.

Sound Sources:

Swan Violin
Pianoteq (Petrof 284 Mistral, C. Bechstein D 282)

Temperament: Meantone 1/4
A=432