I finally thought to look at the Philco parts value charts which I had downloaded last year from Philco Repair Bench. Indeed, the mica condensers pictured above agree with Philco's older, unique/non-RMA coding.
Example:
It appears that in the mid-thirties they were transitioning to RMA, but had only applied it to newly developed components at first. So in this set, all the resistors are RMA, but the mica molded caps have Philco's old codes.
Now I can sleep at night.