How would G'raha Tia know any more about how electrope works than say Sphene or any of the researchers? We just recently learned about it even existing.

Not only that, but isn't there a shortage of the material to begin with? The whole war between Lindblum and Alexandria?

Is it because of the method using white auracite and his blood, which was done by Beq Lugg on the first?

I don't really understand the line of questioning, given the events that transpired during the story. Changing that one part doesn't change everything else that happens, from the already existing shortage of both souls to create new endless and of electrope. On top of that, Sphene outwardly refusing to cooperate and double down on her goal to slaughter everyone.

It's an artificial aetherial sea and we returned the people who died back to the real one so they can be reborn. Souls in ff14 are weird, and we don't fully understand how they work.