If the creature respawns are working everywhere else, then it will be working in Andris too. The creature spawns are all in one file, so the only thing i can think of is if Andris' creatures are slowly stocking up on a small island out there somewhere due to the regioning of Andris in said files.
When i get a chance i will look over the file and adjust Andris' region if required. Apart from that, the only thing i can think of, is that the creatures will be there, just hidden somewhere in the forest where you havn't looked yet.
Are you talking about Sea Serpent specific spawns or the creatures on land?