Yeah that's interesting to see laid out. Weren't we lead to believe Wutteät was dead before WLW came out? I know there's the story about Ciogli breaking its neck -- which after discovering that Wutteat is still "alive", seems even more like a history-embellished legend. I'm wondering if the text ever explicitly said the dragon was dead, or simply defeated. Either way I assume his weird undead state is unique to him, since otherwise there shouldn't be any stories of dragons dying, embellished or not (Nau-Cayuti at least seems to have definitely killed Tahnhafut, since otherwise the tale doesn't really warrant the attention it gets if he just like, beat the thing up until it flew away).
It's also weird that so far, Wutteät is our only example of something being "undead" in the particular way that he is. All the other life we've seen is either ensouled (which includes Ciphrang and denizens of the Outside), or an automaton. The idea that he can only die when the World ends (which I assume is synonymous with "closing the gates to the Outside") is so different from anything else we are familiar with. It's not even really something that the audience could have guessed was possible given what we know of the metaphysics so far, so I'm curious how important that little detail is and whether we'll actually have it explained, or if it's just meant to be a bit of colorful window-dressing (and an excuse to have another truly ancient character aside from just the Inchoroi brothers, who are otherwise the only POV's to have firsthand accounts of prehistory).