First of all, can you stop taking this so damn personally? You act like I basically just typed "hur hur you're a retard" and left it at that. I gave a well thought out rebuttal and I didn't attack you at all, so quit acting like I have. You and i go back a ways so its disappointing to me that you think im attacking you and are neg repping all my comments (as well as the others of those that disagree with you, but do what you like i guess) And yes, I've read thr entire thread.
Oh, I see. I think there was a misunderstanding. When you said: "The amount of overanalysis in this thread is astounding. " it came across as mean to me. However, it's difficult to determine the tone of what somebody is saying on the internet. So, never mind my harsh tone. Also, I don't actually downvote people who disagree with me. I only downvote when I think somebody disagrees because of an argument I think is weak. For example, Lelygax disagrees with me too, but I never downvoted him. But I disgress.

OKay, that I understand, but again, if this "mystery woman" (who I'd never heard anything of until I read that Worlds Of Power Simon's Quest book growing up) was SO vitally important to the game's story, why is she not mentioned in game? Why no exposition at the beginning, why does no villager mention her, priest in the church, etc? And given all that, that we have no idea what on earth the designers were shooting for, this is all wild speculation and we have no reason to distrust the game or its endings based on some theory that involves a plot element that wasn't even important enough to be included in the game. If you want to talk about intentions, I'd say that is a big one; that they didn't include her in the game at all.
As someone who grew up in the NES era, played tons of games and read tons of manuals, I've never heard of a plot element that is vital to the story NOT being at least referenced in-game, and I doubt they'd let some story element get in the way of making another game, especially back then.
It's important to note that the mystery woman and Simon's girlfriend from the Worlds of Power novel are not the same character. They just happen to have similar roles. I doubt the author was aware of the Japanese storyline at all.
As for your actual point, it may be weird that such an important element is not mentioned in the game itself, but it's definitely canon. For example, the guidebook of the game mentions Dracula has a sixth body part, and that he is revived through this body part when Simon burns the other five in Dracula's castle. You would think this is something wacky the author of the guidebook came up with, but the PoR timeline I mentioned earlier mentions it too. Therefore, the information is definitely legitimate. It also mentions the mystery woman. So, I don't think there should be doubt about the reliability of the manual story.
I think you're reaching with this. Do we know that it was essentially the same team that worked on all those games? I've been under the impression that they changed team members pretty frequently back then. And I don't think them using prequels is proof of anything other than them trying to change things up and have a different character in the spotlight. The GB titles really didn't have any story elements contained therein, hell I thought I was playing as Simon in CVA until I joined the Dungeon here and it turned out it was Chris, because there's no reference to his name or any sort of year in-game or in the manual, at least not the American one.
H. Akamatsu is the director of all three NES games. The director of Castlevania IV confirmed this in an interview recently. He mentions CVIII was made by "the same people who made CVI and II."
As for my "they never picked up on the cliff hanger ending" argument, we have established earlier in this thread that IGA treats the NES and GB games as canon but sometimes straight up ignores things from them. However, assuming the cliff hanger is the originally intented ending, why do both Rondo and HoD, both direct sequels at the time of their release, completely ignore it? He ignores a lot of things but I can't imagine him ignoring such an important story hook. That's one big reason why I don't believe that ending is canon.
As for Nagumo, I think she was referencing the timeline that came with PoR, which again, is using information that crystallized well after SQ came out to prove her point. It was in a post about halfway down on page 2 of this thread.
I'm very confident it's in the Japanese manual as well. However, I only have acces to one translation, which contains some errors. For example, it makes the same translation mistake made by TheouAegis earlier in this thread. That's why I think it's probably in there somewhere, but the translator just skipped over it or something. Also, the PoR timeline only takes information from earlier sources. The mystery woman and Dracula's sixth body piece weren't original invention, so why should this be?