Holy necroposts Batman.
In any case, there isn't really any "leak" that can reasonably be fixed, as the third party programs in general function by reading data that's being sent to the game client.
Client-side data is like an open book, but server-side data is much harder to get access to in order to read/modify, and while handling more data server-side can prevent cheating, it also slows down the gameplay. For an excellent example of this, it's the reason why chocobo races at the Gold Saucer have such a massive input delay as everything is processed server side in an attempt to prevent cheating via methods like speed hacks and such...but it still doesn't prevent cheating done strictly through client-side methods like the bots that just spam races endlessly.
Though looking back on things, hunting is somehow more sane at the moment then it was back then even with crossworld being a thing now...at least on my DC.