Wouldn't it work if CS8421 is set to slave input/output, input set to RJ16bit, output to 16bit i2s and then to WM8805 HW mode, master set to 16bit i2s input (MCKL output would be 256fs=11,2896MHz)?
Input and output in slave mode, cd player is master to the input and transceiver to the output. The module boards on aliexpress are cheap. If you don't succeed it will not be financial disaster.