In a split table LMT gain is decreased until LMT Index Limit+1 is reached and LPF gain is decreased. Once LPF gain is decreased to 0 LMT gain index below LMT Index Limit is reduced. More detail in the image below.
In AGC slow attack mode, gain change only occurs if a threshold is exceeded (Inner Threshold Low or High or Outer Threshold Low or High). If large LMT overload occurs there is an option provided to reduce gain immediately and not wait on counter expiration (Reg 0x123).
I would recommend looking at Slow Attack and Hybrid AGC Registers in UG-671. Control bit descriptions will give you better insight in the algorithm operation and available control options.
Full gain tables maximize sensitivity and split tables are better at maximizing distortion/blocking performance.
There is no characterization data available for phase vs AGC index for RX1 and phase vs AGC index for RX2.