Doesn't matter, it's still a sexualized depiction of a child, and that's reprehensible. 

What about games where you kill children? Are they reprehensible too? Should they be edited altogether?

The only games I can think of in which children are killable use this as a morally bad issue (like Bioshock.) Most games don't even let you kill children (see: Elder Scrolls.) 

Can you name a game in which killing children was seen in a positive light? 

I'm not sure what you mean as positive light, but sure. You could murder children in the original Fallouts, Deus Ex (which even had exclusive dialogue when you killed certain kids), Postal, and let's just not forget Drakengard, where Caim remorseless executed hundreds and hundreds of (albeit soldiers) kids.

In the original Fallout everybody hates you if you kill children. There are negative consequences. Can't recall the specific scenario in Deus Ex. I haven't played the other games so I can't say. But I really don't see child murder all that common in games, nor are there many people bothered when they can't murder children. 

What I mean by positive light is that in this game (Xenoblade Chronicles X) the pre-teen (almost) nudity is fetished and considered a desirable feature that people want so much they are outraged when it is not included in the localization. Most people don't want child murder in their games for the pleasure of it. If it is included, it is because it tells a moral story or represents a moral fault in the character (you are punished for it.) It is not fetishized nor glorified, with the odd exception of course (and people complain when this odd exception exists.) 

In the original Fallout everybody hates you regardless of what you do. This is a trend that follows in every game, except for the fact that after 3 you can't kill children anymore (And they went the extra mile so that you hated them to death). There's no moral dilemma for killing them or not; you can do so if you please. It's no different than killing entire populations in any Fallout game. It's not a moral fault in the character because the character is pretty much controlled by the player. But sure, you could say "you're given bad karma", so you might have a point here.

As for your definition of positive light, I guess the Deus Ex example still stand. You can kill children free of consequence, they have an specific, exclusive NPC kid scream, and there's even a dialogue for killing a rather annoying child in Hong Kong (so the developers anticipated the player would do that). You can pick up their bodies and dispose of them afterwards or just leave them dead on the streets. I've never seen anyone complaining about this game to this day (it is still remembered as one of the greatest games ever made for some people), nor for this specific feature. At the end of the day, it's just fiction, and children shouldn't be really protected by a "moral armor" when your character can (and probably will) grow up to be some nasty genocider.

In Drakengard, death is fetishized upon. Caim is encouraged to kill as many children as he can (Save from Leonard, who kindly ask him not to do it, which is...kind of funny, considering Leonard is a pedophile) and not to have mercy on them. Everyone gets punished at the end, but that's because of the developer's vision (who considers that no killer should have a happy ending, and that's a theme present in all his games), not because the main character lacks ethics. Again, Drakengard is regarded as a cult game, disliked by some because of its gameplay mechanics, but loved by many because of how weird and dark the game is.

And then there's Postal, on which doing whatever you want is encouraged. Killing children is among the least horrible things you can do. Although unlike the previous two examples, I kind of guess a lot of people hate these games (they're very bland too, so it shouldn't come as a surprise xD).

they could have raised her age 

and who says that changing Lins outfit to what ever you want is seen as a good thing by the game? You can kill children in a lot of games, MGS5 for example. And some opnely play with the subject like Silent Hill Downpour in cutscenes or DMC Devil May Cry

But that would be censorship, or some say, localization, too, no?

no, removing skins, costumes, or changing them is for me. The age are just some pixels if it is displayed in the game in the first place