The question is "have you ever".
Not "do you think we'll be able to find out".
If you get caught after you start ground school, your career is toast. And you're unemployed toast (unless your regional has some sort of snap-back provision for folks who flunk out of majors).
That's the risk, would you rather be senior and stuck at a regional, or fired by a major (PRIA reportable)... and starting all over again at a regional?
It's possible that depending on specific state law (airline HQ state, and possibly your residence state), that you might be protected because the conviction was dismissed. But you'd have to do a lot of research, and you would probably have to sue them after you got fired. Good Times.