If you're dealing with multiple processes persisting data to different data stores, you're dealing with a distributed database problem, which has many more fail

If you're dealing with multiple processes persisting data to different data stores, you're dealing with a distributed database problem, which has many more failure modes than the ones you've described here. If there's anything I've learned across my career, it's to avoid distributed databases unless absolutely necessary, and if it is necessary, then spend a bunch of time trying to make sure you got it right. And then even after that you probably got it wrong.