Welcome to the community. 
The trainer has not gone.
Since REPPiN is retired from WeMod and therefore will no longer be updating this trainer, it has been merged into the most updated trainer we have for the game, which is here: FINAL FANTASY X/X-2 HD Remaster Cheats and Trainer for Steam.
If you click the History button in the trainer (under the Play button), you’ll see the previous trainer versions by REPPiN listed there.