You forget about Rice’s theorem. Termination is not that exciting, but the existence of race conditions and a million other properties are - and those are not possible to prove true in general.
Rice's theorem states that those properties can't be automatically decided in general. But that's irrelevant to this discussion, because this "magmide" tool doesn't claim to do that. It merely checks proofs that have already been found (e.g., by a human), which is trivially decidable.