I think there's nothing wrong with them, but only if the question is directly about the studio or author in that tag. But the author's tag should not be used on every question about an author's anime just because they happen to be the author.
Take this example:
"How much contribution did author XXX make to anime YYY? Is it true that along with working on the story, he was the one who suggested to change the character's hair color from green to blue?"
No matter if this question would be on-topic or not, it could have used the author's name tag, because it's rather about the author than about the anime. If, however, it was phrased like
"Who made the decision to change the character's hair color from green to blue?"
it wouldn't deserve the author tag anymore.
So these tags should be used carefully, and questions that use them improperly should be re-tagged quickly.