I am far from convinced that there are many "spurious protection triggers" or "dumb designer mistakes". No, I am not a pilot, but I have been intimately involved in real time safety critical software design, realisation and testing.
And yet, out in the real world, physics and reality stubbornly come up with scenarios and combinations that you had not though about.
I am a pilot and I can testify to the thousands of spurious faults and messages an A320 comes up with. Most of the time Ctrl/Alt/Delete does the job. Sometimes sadly there is no time for that sort of thing. A humble attitude and a very heavy dose of realism is an essential attribute of any engineer dealing with safety critical systems