If you can't stop them from doing it anyway, make a legal version that makes the illegal one obsolete- otherwise the only people being punished are the ones not cheating. Right now teams that do not cheat, like me, are at a disadvantage. I train my own 18 and 19y/os. Few else do that. Many have a farm somewhere else or just watch teh TL for the products of their farms. This lowers the value of what I am doing signifigantly, since there are so many farm teams completely devoted to training, my guys aren't rare.
i have 50.000 farms even without cheating ;) because i look at the tl, for players other dudes have trained. it is always faster and easier to buy the player you want, them make another team and train them yourself(maybe even farming 3 season money to even buy the trainee you need, just to discover after additional 5 season training that some other dudes wants the player too and give more money ;))
And you say it yourself, your guys aren't rare, the "farms"(i like to call them other managers) also producing them so that you could buy them on the TL instead of wasting 8 seasons to train them with a second team.