Burt Carroll was certainly using S+Au sensitization, but not in the form we know it today. You have pointed that out from his articles when he was at the NBS, but whether he knew at that time that Kodak was really using it and it what form had to wait until after he joined Kodak.

Confusion arises over the correct time to add the Au, and this was caused in the early days when active gelatins were in common use. They supplied the Sulfur and so the exact timing was "when?" because heat and Sulfur were already there! Here is the current sequence.

Precipitate nuclei > ripen or digest > growth + dopants > vAg adjust > wash > Sulfur + Gold + heat + time > spectral sensitization > finals (doctors) > coat.


Ripen = heat and allow grain changes with no solvent addition.
Digest = Ripen + Silver Halide solvent present
Dopant = some metal or organic compound that changes the emulsions properties
Finals or Doctors = anything that changes the properties of the melted emulsion or the coating
Sulfur = NH4SCN, NaSCN, KSCN, Na2S2O3, (NH4)2S2O3 alone or in combination
Gold = there are so many possible compounds I hesitate to mention just one!