Brandon Sanderson?! As you say, that's not going to be over anytime soon!They were just narrated if i remember correctly. Overlord is by the Chris Gurrero who voices Aniz in the English dubs so it sounds nice and authentic as a dub watcher myself.
Reincarnated had 2 narrators Casandra Lee Morris for the girl protagonist point of view chapters and a guy (can't remember who) for the fathers point of view chapters. It's a trick I've seen a view times in audiobooks with multiple pov characters which makes it easier to follow along and know where you are in the story.
Both were well acted and I'll be continuing both series alongside other audiobooks I listen to. (Currently on Rythm of War by Brandon Sanderson which is 57 hours long so will be a while before I listen to Reincarnated 2)
But thank you for the information about the LN narrators; that's really helpful - and good that they used VAs connected with the original dub (well, in the case of Overlord, anyway).