Which event? The current event where you kill Yuffie for exchange currency has worked for me since it dropped.
If you’re referring to the new competition event dungeon, I wouldn’t advise using the trainer there, as the score is ranked against other players and they’ve already stated anything that stands out there will lead to a suspension.
The cheat works flawlessly for any solo content–I’ve cleared all floors, all story, and just about everything else that doesn’t have a multiplayer aspect to it (don’t use it in coop matches). I tried using the game speed adjustment to make materia/chocobo missions go faster; it worked once but since then has stopped working, but I would be wary about using that, as well, as it may be something they could easily see and lead to suspension.