I feel like the author not grasping the difference between Hiden and Kekkei Genkai (or even deliberately changing which category a technique sits in, which is also a possible explanation) is going to be a relatively minor sticking point for some people, especially when it's a clan that doesn't get that much screen time in canon, though I can definitely see how it could be very irritating.
I am still reading it, I am having severe internet issues at the moment so I haven't been able to update the post with everything else.
The Omniscient "Council" makes a comeback with a vengeance as they decided (instead of the Hokage) that Sasuke was to live alone in his compound. There are numerous problems with this The Council or The Civilian Council are a mix of fanon and actual stuff. Like, you have the two advisors of the Hokage and they help coordinate with the Hokage on important matters, but they just, advise. Is Up to the Hokage to listen or not.
I'm generally pretty ok with author's changing setting details to better fit the story they want to tell,
Its a Big Change because its used to make the SI/OC onto a special snowflake among his clan. The way it was worded, he's a telekinetic, not a telepath. He's a "mutant".
We also have... like obscenely wrong details on Sasuke's personality
pre massacre. He was a cheerful kid and probably would have gotten along Naruto. He isn't this... bitter kid, he only becomes as much after Itachi mind rapes him.
The fic is written in first person POV and while unique, it feels too tell and little show, for example: the SI/OC has "pangs" of jealousy towards Ino bonding with Sakura as friends, but we never see this "jealousy" we are merely
told about it.
Another problem is that he is put on a "separate training regime" we... aren't told what is it about, what it does, or how is it done, only he gets put on it and then he isn't, we are also never
shown this training, he only tells the audience about it which is a re occurring problem.
Sakura also vanishes entirely off the story without nary an explanation beyond "she and Ino aren't friends because they both like Sasuke".
the toddlers speak like adults
This is something I tend to give a pass because its honestly, difficult to write kids (I know, I am trying to write a 5 year old Ash Ketchum and he sounds
horribly like an older person would, sans the pronunciation problems here and there) so I can see why authors fail at this.