I would love to have an update for this, too
couple things:
1- I just installed the game from scratch, downloaded the trainer from here, tested it, it still works.
some tips:
1- like the instructions say, don't activate the trainer until you are actually playing the game (i.e. NOT at main menu but IN THE ACTUAL GAME)
2- easy way to ensure it works (works here) is to run the game, start a level, go ahead and place at least one turret, alt-tab out of the game, start trainer, press F1, alt-tab back, use options..
best,
Cal