Maple

What would be the point ?

I just hope this story isn't just about multiverse travel (and the voting list wasn't really appealing so...).

Okay... everything is moving too fast. The parents discover that their two-year-old daughter has changed overnight but no problem. Petunia approaches Severus, and without any prior interaction, she declares that she already knows his wizarding status. You really need to work on the pacing of this story. Everything goes too quickly, no scene is developed and your character accepts too easily the things that happen to her : "Oh ! Am I reincarnated ? Great. And in the world of Harry Potter ? No problem ! And I have a system ? Who would have believed it ?" ... Do you see the problem ?

You're speeding things up a lot.

She accepts her situation a little quickly, doesn't she ?

Isn't Petunia older than Lily ?

Not an horcrux. No scar.

No. He said it correctly: "moldu" means "muggle" in French. And we know that the Flamels speak to Harry in French from time to time. Or they slip into their native language without realizing it.

Cal Kestis survives Order 66. He runs away and hides to become the hero of a certain game series.

Bought then abandoned ? Captured then trafficked... and then escaped ? There's many possibilities.