SignalTap II fails to acquire events

I am a bit sceptical about safe state machines concept. A good design should not enter undefined state. If it does due a glitch then any logic may go wrong and not just that of state machine.

So exiting from wrong state will be futile if other logic fails. We must first trust our logic or we can't design. For critical applications yes it is mandatory to recover from a fault and that requires considerable care in design and testing.

That is some areas of aerospace, medical devices etc. where self recovery of logic is crucial. In other cases we are used to apply reset or power cycle or even bang on the box.