How very interesting Bruce, that you talk about Alan Lomax and his uneasy relationship with the accordion(s), diatonic and chromatic.
His archive contains pics of melodeons and PAs in Italy and other regions.
Alan Lomax has devoted his life to music and folk music, I have great respect for the field work he has done, and all the documents he has left us for posterity.
Do you know his Cantometrics system and theory?
https://en.wikipedia.org/wiki/Cantometrics#History_of_the_theory
But regarding accordions, in my humble opinion, he made a mistake many folklore scientists and musicologists have made before.
Music is never a static art, it is always a living art. Music and musical instruments have always been subject to evolutions in time and geographical border crossings.
The classic mistake is to define the phenomenon of folk music. The word definition has the concept of ending in it, the latin expression finire , to stop, to freeze.
If you search for a definition of folk music, in a way, you kill or stop the flow, the evolution, life.
Music is part of life, always in evolution.
You can not stop the evolution of inventions of new musical instruments. People have always adopted new musical instruments in whatever musical styles, be it folky, jazzy, classical, ...
The accordion or accordions have every right to be called folk instruments, or jazz instruments, or classical instruments, ...
People switched from bagpipes, fiddles, flutes, ... to accordions, simply because they are very practical instruments. If accordions were not practical, folks wouldnt have embraced them and integrated into their musical life.
Another mistake folklore scientists make is to overemphasize the oral tradition or transmission of music as the only way music passed from one generation to the other. There has been a mixture of oral and written transmission in folk cultures.
Folk music and classical music both influenced each other.
Maybe some folklorists tried to put up a fight against the chromatic accordion, and even the diatonic accordion.
In the end the accordion(s) won
In the end scene of the movie The Fearless Vampire Killers the Professor Abronsius is helping to spread over the world what he has been fighting against...