I checked the data taken on 4/21 again and compared with today's measurement.

4/21 measurement
optical gain = 15.7 ct * 4 * pi / 1064e-9
= 1.85e8 ct/m (from displacement to POP17Q_ERR)

C_mich = optical gain * input matrix / laser power norm
= 1.85e8 * 0.6 / 2.48
= 4.48e7 ct/m (from displacement to MICH_IN1)

(A_bs * C_mich) is shown in figure 1.
A_bs = (A_bs * C_mich) / C_mich
= 5.63e-11/f^2 m/ct (from BS_ISCINF_L_OUT to displacement)

Today's measurement
optical gain = 13.0 ct * 4 * pi / 1064e-9
= 1.54e8 ct/m (from displacement to POP17Q_ERR)

C_mich = optical gain * input matrix / laser power norm
= 1.54e8 * 1.0 / 2.64
= 5.83e7 ct/m 5.83e8 ct/m (from displacement to MICH_IN1)

(A_bs * C_mich) is shown in figure 2.
A_bs = (A_bs * C_mich) / C_mich
= 6.28e-11/f^2 m/ct (from BS_ISCINF_L_OUT to displacement)


These values are consistent with Ogaki-kun's value (klog11754) and Kokeyama-san's value (klog14548).
In rough estimation, the largest error is in the estimation of the optical gain (~2 ct = ~15%). Coherence of the transfer function measurement is almost 1.0.
As Kokeyama-san mentioned in klog14548, maybe klog14265 is typo.