Yes, an end of course check at a self examining school is a checkride failure, AFAIK. If you filled out an 8710, and the ride would have ended up in you getting a crisp new temporary certificate, and you didn't get it, that's a checkride failure whether you have internal examiners, a DPE, or a local FSDO FAA examiner. Stage checks are not a checkride failure. I also had an airline ask me in a telephone interview if I had ever failed a stage check, as well as being asked about checkride failures. Luckily, I've never failed a ride. But, I knew one guy who failed every checkride he ever took at least once, and still got hired on his first try.