the insert lamps are strobed to keep the filaments warm, if you have Leds fitted then this strobing can cause some leds to "ghost"
the patch increases the delay between clearing the row / column data and writing the next row /column data. so more off time.

WMS changed the code for wpc95 games (they added a 30uS delay) so the patch changes the wpc and wpc-s lamp code to wpc95 lamp code.
i may have interpreted the explanation wrong but thats what i believe the patch programmer was trying to say

so more off time in the strobing

if you use "AC" leds for the G.I. then you will lose the flicker effect until the G.I. is dimmed. there is no way to stop led flicker once the G.I. is dimmed without modifying the G.I. circuit

using leds for G.I. reduces the load on the G.I connector on the driver board (WPC and WPCS) and reduces the heat emitted from the diodes used in the G.I circuit on wpc95 (where fitted)