No, the plot twist was that Sakura was not her biological mother. A plot twist of plot twist is really retarded.
It would be bad writing because Sarada would not have any lesson to be learnt.
At the start of Gaiden Sarada was questioning the Ninja way, she didn't understand it.
Naruto told Sarada that there is no ninja greater than Sasuke, and based on what Sasuke's doing, she could learn the value of Ninja, and be inspired to become one.
Sasuke hasn't been with his family because he was on a mission to save the world, Sarada will learn the importance of Shinobi, and their duties from learning about her Farther, and hopefully her Uncle. Sasuke is sacraficing his own personal happiness for the greater good, similarly to Itachi aswell.
We've already seen her in the movie promos with a headband so we know she's a Ninja, something clearly happened to motivate her into becoming a Shinobi.
The main part if Gaiden so far has been Sarada, and her family, so it wouldn't be a surprise if these events connect her with her parents, after all this is a Shinobi family. These events will connect them, and strengthen their bond.
According to Sarada's reasoning you shouldn't help someone who didn't give birth to you or related to you.
She's angry at the moment, she's also a 12 year old girl. If she really continued to dislike Sakura then i doubt she would continue to wear Sakura's exact same outfit in the movie which we know takes places after Gaiden.
There's a good ending to this whole situation.
But you and I know that is and will not be the case as evidently from the manga. Sarada stated that she has been keeping quiet on the matter for a long time, meaning that she has always been suspecting that Sakura may not have been her mother. The poor kid deserves better. Sakura has fed her with lies and it's clear now salad is angry at her because of it.
Ofcourse Sakura's lied to her, Sasuke is on a top secret mission, and told them not to tell anyone about it, that includes Sarada.
About her medical records of why she wasn't born in Konoha. We know little about it, there's not much to form a prediction of off, i think.
Sarada was wondering if Sasuke,and Sakura were together, remember when she asked Sakura if she was married to Sasuke?
Well she's now heard both of her parents say they're with each other, and she's their child.