There are lots of ways around this. The most obvious is to forgo the process if the story is one of the few that would draw the ire of a national government or

There are lots of ways around this. The most obvious is to forgo the process if the story is one of the few that would draw the ire of a national government or otherwise place lives at risk. There are lots of cases where anonymous sources are used in less extreme circumstances, and to protect those you could build a rigorous system of vetting notaries, equivalent to a security clearance. Under OP's proposed model we wouldn't need a lot of these notaries, since as I understand it they'd only be actually validating sources if doubts are raised, so the requirements could be quite strict.