Some of my Weaver cars have "CMP" on the bottom; they were at least in Weaver boxes. Don't care - they're interchangeable, to me.
Did not know that Crown did S scale. The comment above about the S tooling being in the "scrap yard" is one that is regularly heard about mystery tooling. In fact, tools are expensive and are seldom "thrown away" unless they are horribly worn or badly damaged in some way. If such a line existed, and the tools were still useable, it is likely that they still exist, somewhere. (Though valuable things do sometimes get discarded through ignorance when a company shuts down, to be honest.)
But, all this is supposition and spitballing. I never heard of Crown "S".