Thanks Marek, that is a great workaround and adequate for my needs.
I am still interested in bringing this to the attention of whoever works on Processor Expert. It looks like the I2S_PDD_PLL_CLK label used in the PE generated code would match the label in SAI_PDD.h if I was using a different processor, but the one I am using (MCU_MK64F12) labels the same thing as I2S_PDD_PLL_FLL_CLK.
If there is a better way to submit a bug report to the PE folks than posting in this forum, I'd like to know about it.