I've found a very silly solution to the "error tone" problem; run the program/game in "windowed" mode before opening and activating the trainer. Once the "trainer activated" sound plays, you can switch back to full-screen and use the cheats' shortcuts (I believe) as you normally would. I can't confirm if a "borderless windowed" mode also fixes the problem. This worked on five trainers with the "error tone bug", for five very different games.
Again, making sure your Trainer version and Game version line up is an absolute must.
All MAF's trainers work fine for me .. Windows 10 creators edition/ Windows 7 .. I always have AV off .. Run my games in windowed mode .. Run trainer as admin .. Make sure that .exe file name is the same .. And a partridge in a pear tree ..
PS if windows/ the game has been updated it can cause the trainer to stop working ..