Glad to hear that you've enjoyed the experience.
GAME_COLOUR= is only relevant is the FP table author turns on the table lighting (RGB_OUTUT=) to use default colours and triggers (ie RGB_STYLE=FLIPPER or TIME). The colours used by the table are at the selection of the table author from the full palette.
When using the FP link and the devices setup via LINK_xx you will need to ensure that your flashers are set as LINK_FLOL, LINK_IL, LINK_CN, LINK_IR, LINK_OR. Also check that you don't have those flasher devices setup as RGB_OUTPUT= devices. When using DOFLinx in the keyboard intercept mode (ie FX2) there is no concept of flashers so its quite possible you have them there. You may need a SUP_INI to reconfigure you RGB_OUTPUT for FP linked tables.
I'm pretty sure the flashers are set to fade a couple of times as the game starts, then a couple of them are linked to the bumpers on the left mid area, and others are linked to the on table flashers, certainly not all white. If you want to look, open up the script in FP and search for "FF_Flasher" that's the command that sets the flashers off.
Let me know how you get on.