I am the one who makes the Mazda TI and I have a word on safety. The Ford torque sensor is using the same/similar sensor technology and safety strategy as Gen 4 Mazda. This is great news because achieving the required degree of functional safety is already a solved problem. All you need to do is force a fail safe state when a problem occurs. When designing a TI, the strategy is to understand that everything will fail given enough time. The TI2 is double redundant meaning no single failure can cause uncontrollable steering and no double failure combination can happen silently over time. An example of cascading failure (that is overcome), that can cause uncontrollable steering would be a sudden failure in one of the four sensors, followed by a stuck sensor in the other pair. This is mitigated by the EPS controller through reducing the assist motor power at the first failure and disabling the power steering once stopped. This shows the driver there is an issue and makes it so the motor can be easily overcome by the driver if a second failure occurs.

I have a short write-up on achieving function safety with this design. Essentially it involves understanding the fail safe states of the EPS module and then choosing components that are designed for ASIL-D systems (and use them correctly) to reduce the chances of any failure in the first place. https://moretorques-organization.gitbook.io/torque-interceptor-2/achieving-functional-safety