@Yadokari
So she refuses to leave the girls she fixes and lives their lives in their stead huh.
im not actually sure but i think the body dies after su lüxia leaves that world.
in the harem world, su lüxia only stayed those additional 10 years so she could "finish what they started" i.e. not leaving the 4th to fend for himself after getting him into that position, and they didnt react to su lüxia getting sick and dying, so maybe the system arraganges for the body to die when the host is on the way out.
but yeah, i think it's just "helping the original owner get their revenge on those who betrayed her so she can rest in peace", and not "helping the original owner get revenge so she can go back to her (now fixed) life"