That's the problem with time travel: Either nothing matters or nothing makes sense.

There exist three different G'raha Tias across various screwed-up timelines, as well as now four different versions of our WoL. If things didn't matter, all the past WoLs and G'raha Tias would be overwriting the future, destroying the story as it is and maybe even leading to the star never being sundered (or maybe it does, since the WoL in that past is technically a future version of a WoL from a different past). But you can't do that in a game, so things just don't make sense instead.