I don't understand what you mean. Even limited time breedables are listed as breedable in the Codex such as Admirerer and Pisces.
@Fireball, I agree about the disparity between the two sources. I really thought the Honeycomb would be breedable since it has been for the last however many times it was released. I was going to try for it before I checked the Codex but have now decided not to waste my time on something that may or may not be breedable.