[Banknorris]

Maybe you can replace the function CombatText_AddMessage, this will taint Blizzard_CombatText.lua but hopefully there is no secure stuff involved. This also assumes you can identify the separator in the message parameter of this function. I mean

CombatText_AddMessage_old = CombatText_AddMessage
function CombatText_AddMessage(message, scrollFunction, r, g, b, displayType, isStaggered)
    --code to identify if message contain LARGE_NUMBER_SEPERATOR and replace it
    return CombatText_AddMessage_old(message, scrollFunction, r, g, b, displayType, isStaggered)
end