I quite liked the first episode and don't mind Pedro being Mexican, Sarah being black but, for me, Elle really did need to be a younger looking actress (despite thinking that Belle is a very good actress) because the point of the game is that the player (or the viewer watching Joel) should feel protective over her specifically because of her young age - she's a literal child, not a 18/19yo teenager - which Joel eventually becoming a father figure to her, so an actress who doesn't look like a "child" can't create that same visceral "dad protecting a little kid" vibe thats the whole arc of Joel's story and when that fails the rest of the story starts to fall apart.
So yes, Elle appearing to be "young" at 12-14yo (irrespective of actress age) is absolutely essential for the rest of the story to work!