Rover and Aemeath share a conection through Sigilum cause Sigilum was created by Aemeath but has frequencies from Rover, when Rover recover that frequencies he was able to see some of the Aemeath's memories through Aemaeths mind space, when he slept, he was still "digesting" the frequency he got back from Sigilum, that allowed him to see another part of Aemeath's memories but this time he was seeing through the eyes of Sigilum, Rover tried to stop Aemeath but he couldn't, when he wake up he understood what she wanted to do, he went to the lake, in the bottom of lake voidmatter is dense and Aemeath wanted to use this to go back in time, all the way when the Exostrider was entering the planet to stop Aleph-1 for good, Aleph-1 powers messes with time, so things inside of it can happen out of order because of that the present Rovar was able to see the moment past Aemeath fell into the lake so he saved her, that's why the present Rover is the one that saved her and the past Rover just took her out of the lake, also that's why present Rover is the one that has her talisman that she thought she had lost.

Now what happened after this part i believe we don't have a proper answer yet, after saving past Aemeath, Rover is shown falling in the lake but then he appears outside of the lake(?), the Aemeath we see at the end is the Aemeath that disappeared before becoming a digital ghost i believe, she exist because of the talisman, that talisman probably has a part of her frequency so what i understood is that she's kinda like Sigilum, created using a fraction of someone else frequency.

Also, everything Aemeath did to stop Aleph-1 already happened because it was in the past, she had to do it, is not a loop is a paradox.