The game tracks it already; the game knows if you've done a roulette for the day by preventing you from getting the roulette bonus more than once if you sign up for it multiple times in one day. The only actual coding that would need to be done is re-using the same coding that the savage clear check system uses to check weekly clears when the party leader sets 'duty completion', but change the flag to the one that keeps track of the daily roulette bonus. Could probably be done in like <1hr.
The actual question the devs would be asking looking at a request like this is, when its super easy for people to just say "I've done this roulette today" and talk with your party members, what purpose does this feature really serve?