What about more complex cases, such as the obvious infiltrator in the same region as a noble, yet he is 'not identified' after the attack? We all know who did it, but he wasn't actually caught... Does it become metagaming to link the attacker through a scribe report placing him in the region?
I don't see how. All that is completely IC information.
Or torture reports, where it is impossible for the information itself to be fake unless it was fake for the original recipient?
I'm not sure what you mean here. Are you asking whether it is metagaming to believe the messages obtained through a torture report without question?
If so, I'd say that's more of a borderline case, particularly given what we know today about the unreliability of information gained through torture. However, in general, I would say that yeah, it's acceptable to declare that our characters "know" that such information can never be false.
(At least until we coders can figure out a way to
make some of it be false...)