These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Les Yay: Isabella's undisguised jealousy of Catherine's budding friendship with Eleanor Tilney can easily be interpreted this way now. Isabella's friendship with Catherine from the very beginning had overtones of this, particularly when Austen mentions how they always "joined arms" when they were together... That is only a modern construction, though. In the context of the culture, women holding hands (or joining arms) was a perfectly natural gesture of friendship which had nothing to do with their sexual orientation.
Jane Austen:(narrating and making a description about Catherine) By the age of fifteen, appearances had mended, and Catherine was in training to be a heroine. (the story continues and it is implied, when the girl gets a proposal by 20-something year-old Mr Tilney , to take place the same year).
However it is later precised that they find happiness in their marriage at the respective ages of 18 and 26, which means still that they were probably, at the time of the meeting, 15/16 and 23/24 years old.
(In the original book, she's beginning to blossom at 15, but is 17 by the time she goes to Bath).
The Setting Update version from The Austen Project doesn't change this at all, with the result that John comes off much worse much more quickly.
Weird Al Effect: This is much more studied these days than the literature it mentions. To the point that most readers thought Jane Austen invented most of the Gothic titles she listed, turns out they're all real.