Trying to make sense of some issues with the Throne of Heroes time paradoxes. Excuse the long rant.
So the Throne of Heroes is known to exist outside the time axis but does this mean that a Heroic Spirit who exist there have knowledge of every possible timeline of their existences? Evidence shows that this is not the case, or at least it is not the case for their Servant selves, as each Servant clearly only remember one personal timeline. In the original Fate Stay Night, Servants did not remember any other instances of their summonings, as they are just reflections or avatars of the Heroic Spirit and not the actual Heroic Spirit themselves, with a few special exceptions such as Artoria, who has not yet died and did not come from Throne or Heroes. In FGO; however, this does not seem to be the case anymore, which really complicates things cuz it means that not only does the Heroic Spirit remember every possible timeline of their lives but also every possible timeline of every possible summoning of every possible timeline, making everything a cluster-fuck.
My theory to explain this is that while it could be possible for Heroic Spirits in the Throne to have memories of all their timelines (or at least timelines where they do qualify to become Heroic Spirits), when a Servant is summoned to a specific timeline, he will only have knowledge of his history in that timeline. Or it could be possible that an infinite number of versions of a specific Hero could exist in the Throne, each for a different timeline. But how does this explain Emiya, who comes from a timeline that is very different from the ones Shirou could take? Perhaps its because he comes from a timeline that is still open to the current timeline that he is being summoned to, meaning you cannot summon from a past that is on a different time axis but summoning from the future is less restrictive? This is assuming that each timeline isn't already set in stone, meaning that the "Fate" and "HF" route are just branches of a shared root timeline rather than being entirely different timelines altogether.
How then do you explain FGO, where the Servants summoned are from timelines that are CLEARLY mutually exclusive to each other and to the FGO timeline itself? Examples are Artoria who is familiar with Emiya, Jeanne who remembers events of Apocrypha, and Illya who is from the Prisma universe. Perhaps because Chaldea exist outside the time axis, it is able to summon Servants from ANY timeline but since it was originally from the FGO timeline, that is the only timeline that it is trying to affect or it is the only timeline that it can directly travel to?
Lastly, FGO itself is just iffy as hell. First of all, you cannot summon an Artoria Alter cuz she does not exist in the Throne of Heroes, it is not part of her history or legend in life, Alter is created by the regular Artoria being summoned and then corrupted by the Grail. Though I SUPPOSE that since Artoria in Fate Stay Night was her original living self, you could say that being corrupted by the Grail is be part of her life history. Then there's loli Jeanne Alter. My theory is that anything in FGO that is not part of the main story are just jokes and silliness and not to be taken too seriously. Artoria Alter in the Fuyuki chapter can still make sense if she is just a corrupted regular Artoria and its stated that Jeanne Alter in the Orleans chapter is a sort of artificial Servant. It doesn't help that since not everything is written by Nasu, who the hell knows what is canon and what is not?
Forgive me if this has already been addressed in the FGO story, as I do not understand Japanese.