It’s a difficult problem to solve! These sensors are already probably much closer to what you would expect a low-fidelity reliable backup to be than you realize.
A similar thing that happened with Birgenair Flight 301. A wasp built a nest inside the one of the pitot tubes. Which was the one the pilot and autopilot was using. And also being used to generate warnings.
I think validating sensor readings is a hard problem. The validation itself becomes another point of failure and confusion.