Right, I understand ... as I say, non-response is the standard response, and nobody seems to mind. It drives me nuts.
About Smithsonian-Folkways, I'm taking a wild guess that they made bigger files, and downsized them to fit on the CDs. In any case, that was 17 years ago. They (or somebody) could do a much better job now - Mississippi surely did NOT do that job.
Besides a 78 is an antique, and each one is different. (Sit with a collector and ask to hear multiple copies of the same record.) If they started with different 78s, you WOULD be buying something distinctly different.