If Amanda is such a huge fan of the book and has read it ten thousand times, why didn't she notice that Mr and Mrs Hurst were missing? Fair enough if there were going to be too many characters and they had to leave them out of the script, but a lampshade should have been hung, at least.
Why also did she not notice that the Gardiners and Col. Fitzwilliam were also missing? Is it just because they, unlike the others, were just visiting?
When Amanda convinces Jane to ride to Bingley's house, the narrative is the closest it's been to on-track since Amanda arrived. Mary then tells Amanda that Jane will get sick if she's caught in the rain, and Amanda is horrified and tries to stop Jane from leaving. Jane getting sick and having to stay at Bingley's house is one of the larger plot points in the book. What is Amanda's deal here?
There was an added twist that getting sick in the rain could lead to a fatal attack of croup, which nearly happened to Jane in the past.
But in the book, it's Mrs. Bennett's idea.
Why doesn't Amanda take any steps to prevent Darcy from intervening in Bingley and Jane's relationship? She acts surprised when it happens, but its one of the most important plot points in a book she has practically memorised.
She's surprised because this time around, Jane marries Collins.
A better one than the above is "why is Amanda so surprised when Darcy is rude to her?" It only forms the entire A-plot.
The answer to all three points is that this is a deconstruction of the type of fluffy bunny romantic that idealises regency style fiction and projects themselves into the story. Amanda is Fan Dumb personified and only thinks she is Genre Savvy and a fan. Instead of being the Mary Sue she thinks she is, she is purposely nothing more than a really bad Self Insert to display the flaws of fandom.
Why does Georgiana just blurt out what is apparently quite a big secret (the truth about Wickham) to Amanda without any prompting?
It's possible she's heard of what Amanda's been out there doing, and let it out to avoid having Amanda inadvertently ruin the family.
If she insists keeping everything as they were in the book, why does she want to meddle into Wickham's and Darcy's schemes? Those are also parts of the story, even do their share at leading to the happy ending.