I don't know of any airliner reliability software that fails catastrophically to a random state by design after it runs through its redundant systems, leading to loss of the aircraft. They are designed to degrade progressively and hand over control to a human, the moral equivalent of a railroad control system degrading permission to "Restricted Speed". Afterall airplanes cannot stop dead in their tracks without falling out of the sky, since usually that is a bad thing. At certain points of degradation procedures call for a divert to the closest airport etc.
I don't have specific knowledge of the Chinese design, but I was listening to a few railroad professionals speculate on the cause. They suggested it had to do with a design philosophy that was based more on the aviation philosophy of redundancy rather than the railroad philosophy of being fail-safe.
The difference being that if the primary and backup systems fail, you're in a dangerous situation if you rely on redundancy, but everything defaults to a stop/restrictive aspect in a fail-safe system.
So frankly, it appears to me that the speculators have a strange notion of what the design philosophy is for aircraft systems. Aviation philosophy is exactly as much "fail-safe" - which means fail to a safe, predictable, well known and survivable state - as any other. The only difference is that the fail safe state is not a dead stop in case of aviation, since that in itself constitutes a serious failure.
Now that is not to say that serious design mistakes are not made in airline designs like the famous one on the DC 10 of routing all three redundant control circuits through the same conduit.