Can I change the parametric filter coefficients of MAX98089, and biquad and parametric filter coefficients of MAX98090, MAX98091 in real-time?

The filter coefficient registers are not intended to be updated while the device is operating. The issue is that the register values take effect immediately after they are written and since each coefficient occupies two consecutive registers (for MAX98089) and three consecutive registers (for MAX98090 and MAX98091), the coefficient value will unavoidably be incorrect for some period of time while the registers are being written. Incorrect coefficient values can (and probably will) lead to unstable filters for some number of samples, which can cause lasting effects, since the filters are IIR. The recommended procedure to change filter coefficients is to disable the device, write new coefficients into the registers, then enable the device.