[masaegu]

Originally Posted by GinaS

母親は彼女を生み、妹を死なせたことで心に傷を負い、 いつも彼女を妹と比べた。ヴィエラはヴィエラで、自分 が妹を、母のお腹の中で殺したんじゃないか、それで母 親は自分をきらってるんじゃないかって不安な少女時代を送った。

I thought this was saying that the mother was traumatized by losing one of her twins and took it out on the surviving twin, but the Spanish says all the child's guilt was self-inflicted (and ignores the 心に傷). Which is it? Did her mother hate her and compare her, or did she just think her mother hated her, and she was comparing herself?

It only says that Viera thought her mom hated her. It also says that the mom compared the two daughters.

って　＝　と思って

わたしは猛烈に反論したが、実はスティーブが一作だけ 、連中の初期のストーリーをぱくったっていい出したん です。

Did Kellerman admit to plagiarizing or did he just quit because he felt burned by being publicly accused?

Is Kellerman and Steve the same person? It SEEMS to be saying Steve plagiarized on one of someone's early stories. Without context, however, it is impossible to say if it was a Steve who plagiarized or he is the one who said someone plagiarized.

Please remember that Japanese is a highly contextual language and without context, it is often impossible to know who is the subject for which verb.

...,アルコールは嗜まず,...

From a general description of a character. The Spanish makes it sound like he was a drunkard ("he knew no limits with alcohol"), but from various places I've looked online it sounds to me like it means he either simply had a taste for alcohol or he was a connoisseur (but then why isn't it 嗜む or 嗜み?). I can't figure out what まず means, except for "first" and that doesn't seem to apply in that phrase.

He does NOT drink. ず is a negative affirmation.

なぜなら彼らは、それぞれ真実を話してくれたと信じる からだ。
ただ、コホウト氏の話の中に、わたしはある手がかりを 見つけたような気がする。双子の母親をおぼえていると 名乗り出る人がこうも少ないのは、もしかしたら過去に 隠蔽したい何かがあるのではなく、現在黙しておきたい 秘密があるためなのかもしれない。
My trans: Because each of them believes they spoke the truth.
Nevertheless, I have a feeling there is a clue to be found in Mr. Kohout's story. If few people have come forward who remember the twins' mother, maybe it's not because they want to conceal something from the past, but rather, their silence is to maintain a secret of the present.

Spanish trans: Because I think all those interviewed told me the truth.
I will only say that I think I have found a new thread in Kohott's words. If there were so few people willing to come forward to say that they had known her, maybe it was because they had something to hide in their past and preferred to keep those secrets safe under the veil of silence.

Although it's a minor difference between whether he's saying they believe they told the truth (implying he thinks they might unwittingly be wrong) or whether he believes their stories are true, I think it's an important one here, and I just can't work out which it is.

"Because each of them believes they spoke the truth" >> It is the narrator who believes they spoke the truth

The rest of your TL is awesome.