It would be interesting to know I guess. It's a bit before my time, I am sure someone does know more about it than me.
I am literally just a hobbyist who is interested so for example I know that this one has come up a few times looking at parentage:
Phalaenopsis Mount Kaala
Whether it is one of the first ones used for modern hybrids, who knows but those flowers are still being sold in supermarkets today 50 years later. Unfortunately other breeders also sometimes copied crosses so there might even be more than one that was used but had the same parents for example.
looking closer phal doris
Phalaenopsis Doris
was a parent of that one which was created in the 1940's.
If you look at the immedate offspring on that site you can see how many hybrids have been created from it since.
I think looking at google a bit closer the Phal Doris is most likely the hybrid that was used for mass phal production which started about 20 years later.