I think you're making inferences that aren't really there, and perhaps the YB is, too. This style of muffin/popover pan was perhaps the most widely copied design in an era where there were literally hundreds of small foundries putting out reasonably good quality castings. The YB calling the pan with the backwards 10 a Griswold variation is perhaps the biggest stretch of all the variations shown, as the pattern design doesn't really have much in common with variations preceding and following it which have definite Griswold markings (either Erie or a p/n). The addition of the B would strongly suggest a copycat emulating Wagner's designation, as Wagner does not appear to have ever used the #10 in connection with this design. I think the most we can say of this pan is that it might be a copy of the pan shown in the YB as variation 6, with no real substantiation of being Griswold, and of which there is no photograph to compare if the 10 has a slanted 1 or not.