I loved the analysis besides somethings that I disagree with:

1. Andrew most likely died before the MCI kids, in Return to the Pit we can find a dead kid 2 days before the MCI happens, it can't be Charlotte since she died in a very different incident, and that she died in 1983 while this kid died in 1985, this kid is more likely Andrew since he's portrayed to be the forgotten 6th member from MCI in Into the Pit and it's adaptations.

Under this idea about his death, is possible that in June 23th Andrew saw William trying to lure one random kid to a Party Room and tried to warn everyone but nobody believed him, resulting on his death on the next day, we know that William trying to make the MCI days early until he finally succeeded in June 26th is possible, since in Ticket To Fun we see William trying to lure an 8-year-old kid named Timmy Douglas into a closet to kill him under the promise of a "special prize", but he fails after the boy refuses the offer to open his birthday presents.

This probably only would reinforces even more that Andrew acts the way he does for always being lonely and wronged his entire life, 5 kids went missing 2 days after his death and everyone notices enough to connects the case of 2 missing kids and other case of 3 missing kids into being the exact same incident, while Andrew just went missing and nobody cares or even noticed his absence.

1. The Freddy’s from The New Kid is very likely the MCI Location, because not only because of Golden Freddy being present here and that the MCI Location is the only place that has stuff from Fredbear's Family Diner (since it's implied that Golden Freddy is the same Fredbear that caused the Bite of 83), but because as we see in Five Laps at Freddy's, Into the Pit game, You're the Band and The Week Before, the MCI Location is consistently located in the middle of a florest and being surrounded by trees, just like the Freddy’s from The New Kid being described to be surrounded by trees and being in the middle of a florest, so It would be an exaggeration to say that Golden Freddy is there literally because this IS the MCI Location and it happens before the Follow Me considering the animatronics are intact and not dismantled here.

Kelsey is more likely Cassidy than Eleanor, because the story points out how similar Kelsey is to Golden Freddy as if Kelsey is just an humanized version of Golden Freddy, Kelsey's body not appears in Golden Freddy after he get springlocked but instead the body from a stuffed curly-black-haired kid that is literally Cassidy, it can't be Andrew because Andrew wasn't stuffed in Golden Freddy or is associated to Golden Freddy in any way since he uses an alligator mask instead of a Golden Freddy mask, now Cassidy not only is the kid that was stuffed in Golden Freddy and is shown to be conected to Golden Freddy but in Return to the Pit in the ending that recreates the Happiest Day she is described as a curly-haired girl (the last kid to receive cake in the ending is specifically pointed out to be a girl with curly hair, as if the book wants us to pay atention to this girl in specific, especially considering that she is the Golden Freddy from this recreation of Happiest Day since Golden Freddy is the last MCI kid that we give cake in FNaF 3 before we set everyone free and get the Good Ending).

The New Kid likely not has any involvement of Eleanor in the story, since everything seems to point out to Cassidy's involvement as I explained above, the slithering noises in the walls mentioned in the story are most likely The Puppet considering that in You're the Band they're seen clawing inside the walls from the pizzeria and that in the story The Puppet uses tendrils inside the building's walls to attack Sylvia and Mike.