I’ve been sitting on this ask for a while and I’m not quite sure what you’re looking for…? The original never really struck me as anything special–it’s not a bad support, but Nyx has better ones. It doesn’t deal with her guilt much.

Huh, looking at the localized support, there’s actually a few interesting tweaks. (of course, there’s a line added to Kamui’s assessment of her which stresses that she looks like she’s in her adolescence, hahaha) There’s a bit of weird phrasing in “crow’s feet beneath her eyes”–I’ve only ever heard crow’s feet as referring to the corners of someone’s eyes. I wonder if that’s a regional thing?

But this bit…

I showed a gift for magic at a young age. I was known by many as a prodigy. Such was my downfall. I became carried away in my inexperience and lost control of my magic. It backfired, and I have been stuck in this form since.

This is…a bizarre description of what happened…she’s quite clear that she killed a lot of people in the Japanese.

I displayed incredible magical potential from a young age, and I was considered a genius by those around me. … However, that could not last. I got carried away and went on a rampage.

Wait, this too…

Because I respect you, Orochi, I’ll confide a bit of my history. When I was younger, I came into my powers of sorcery. But I was too powerful. Too young. Too immature. One day, I attempted a spell that a sorceress should attempt only late in life. I won’t say whether it went right or wrong. Only that it froze my age.

This localized dialog puts the entirety of the blame on Nyx overestimating her abilities and casting a spell that was too powerful for her. While the original dialog didn’t explicitly bring up her murders, it was phrased in such a way as to imply it.

When I was younger, my talents for incantations surpassed all….Back then, I overestimated that power of mine. And I used too much of such magics in sport. To compensate for such a strong curse, my body stopped growing…

This is a little awkwardly worded, but 遊び半分 is like “halfway playing around” or “screwing around”, something like that. Its usage is contrasted against duty/responsibility–Nyx was not taking her power seriously and using it for her own entertainment instead. She does say that she had overestimated her power, but it’s not the focus of the reason why she’s cursed–it’s just the reason why she treated her power like a game.

Basically, the original line didn’t specify that she was a murderer, but was worded in such a way that her killings fitted neatly into the explanation she gave. The explanation localized Nyx gives localized Orochi puts the reason why she was cursed as something totally different and doesn’t really allow for her killings–it puts the blame as simply casting something too powerful.

The bizarre thing is, the references to her killings are accurately kept in OTHER supports.

(Jacob) When I was younger, I did many evil, vile things. I earned the title of monster. As punishment for my horrible actions, I was cursed with this form for all my life.

(Niles) I heard rumors about you long ago, when I was a kid. The girl who grew up as a prodigy in the dark arts… She wove wicked spells without a thought and brought suffering to all she met. But one day she went too far and paid a terrible price.

(Keaton) I ended the lives of many innocents. Until one day, I cast a certain spell that took its toll on me…I found myself frozen in this state, never to age another day.

These lines are very consistent with Japanese Nyx. But in general, it looks like localized Nyx’s past has been downplayed as a total accident in several other places.

(Silas) My failure to control the magics I wielded resulted in many innocent deaths.

(Hayato) A long time ago, I cast a very strange spell. Because of that mistake, my body stopped growing. That’s why I appear so young.

(Arthur) Many years ago, a magical experiment went wrong, preventing me from aging further.

(Kamui) I became carried away in my inexperience and lost control of my magic. It backfired, and I have been stuck in this form since.

When she talks about why she’s cursed in the Japanese, she often says her curse is because of 代償. Reparation/compensation/etc–it keeps her guilt at the forefront of her speaking of it. Even others speak of her like this (Odin: “As compensation for her curse, she is one with a young body that will not grow…”). In several places, the English attempts to explain the circumstances of her curse in a more literal manner instead–the Orochi support specifies it was a because the spell was for more advanced casters, the Odin support says that the spell stole the lives of a village’s worth of people and gave them to her. 

It’s technically a more sensible explanation, but it removes Nyx’s own feelings of guilt and her own knowledge that she committed terrible wrongs from the explanation.

The more I look at it, the more it looks like to me that the localized translations were done piecemeal. There are times Nyx is fairly mild about it when she talks to some people, like Harold–she only tells him that she was screwing around/being irresponsible. It’s a mild explanation, but it still focuses on her own guilt for what she did, not “an experiment that went wrong”, which could be absolutely anyone’s fault.

It looks like the localizer saw 遊びすぎて, didn’t have any context for it, and outright guessed that “playing around” meant “some kind of experiment” rather than Nyx bitterly referring to her crimes with a childish word. Japanese Nyx says that she rampaged and slaughtered without guilt in other supports–in that context, it’s blindingly obvious that “playing around” is her being scornful of her childish self. The localizer does not appear to have read or referenced any other supports.

In conclusion, it looks like Nyx’s past was largely translated faithfully only when she was completely unambiguous in Japanese; when she was even a little indirect about it, the localizers made up implications or explanations that ranged from “technically true but focused on the wrong thing” (ie, she does mention her own arrogance several times in the Japanese, but it was the arrogance that led to the crime, not the arrogance, period, being at fault) to “complete fanfiction”.

It also has the side effect of making localized Nyx seem quite selfish–she complains first and foremost of her own body, not her guilt at being a murderer.