A question about how to use CIR correctly

I would like to ask why the values I read from the CIR register are all very low. For example, the calculated amplitude of the values I read near FP_INDEX is only over 2000 (in LOS case) or even hundreds (in NLOS case), which is much different from the CIR amplitude given in the application document APS006.In addition, my formula for calculating the amplitude of CIR is
CIR amplitude = max(|real|, |imag|) + min(|real|, |imag|)/4

I also have a question about the relation between THE CIR and the FP_AMPL1, FP_AMPL2, and FP_AMPL3 read from the registers. I see that the CIR amplitude calculated at FP_INDEX is very close to the VALUE of FP_AMPL.