I’ve got no idea. This was 5 years ago, and ultimately this direction did not work.
Epic Athas is my up to date work. CR is wonky at best at higher levels. As a rule of thumb for my Epic Athas work, add +1 CR for every rank of metamorphosis and +1 CR for every salient feat. This is a crude methodology because there are so many ways you could build a character but that’s the best I’ve got.