Depends ... In matter of Tieflings kids imortality its change of single value from 1 to 0 (or other way around, depending on how they implemented it )
But Larian is not the only one who can change things, i would gladly download any mod that will make all npcs killable. Since i simply dislike plot (or moral) armor and concider it butchery of immersion.
I still dont understand why cant we change Race for our hirelings. Lets us play Githyanki as racist as they trully are!