I think I’d expect “episodes/byperson” to include those that have been set in the channel. Otherwise, I don’t think it is returning episodes by person - it’s returning something that’s dependent on where the user added that person’s details.
I can’t think of an easy way to merge a call for episodes/byperson and then podcasts/byperson without always having to call both, and then having to additionally call each episode of each podcast to check if that person has been overwritten.
Seems to me this is something that happens on parsing the feed, I’m afraid.