I also struggled with how to answer the "have you ever busted a check ride" question during the interview process. Ultimately, I decided not to split hairs...the question is pretty straightforward. IMO, it doesn't differentiate between UPT check rides or Form 8s. I know as an AF student pilot, it felt like a check ride, it smelled like a check ride, it was called a check ride, and it weighed heavily on the "big picture" of your overall performance. I didn't go the civilian route but if you busted your private check ride or instrument upgrade, you would have to answer "yes." I realize the civilian evals are for punching actual tickets, something military guys don't do unless they take the military competency exam (highly recommend) following UPT, BUT, is there really a difference?

Like I said, be comfortable in the interview and don't split hairs. What if you say "no" and those across the table respond with "well, what about in UPT?" It's a chance to be honest and also emphasize you learned something out of a setback. That's how I answered it during my interview and all went well.