I'm still playing with the idea that Fanny's appeal to the reader includes quite a lot of humorous exaggeration.

There's been a sprinkling of small examples, such as this from the end of ch16: She was beyond their reach; and if at last obliged to yield—no matter—it was all misery now. Oh, please don't think me heartless. I do pity her situation and admire her moral rectitude. It's just that 'no matter...all misery' is such an extreme position to take, especially as Fanny is fixated on another person's credit (Edmund's), which really ought to be his responsibility, not hers. Then, sure enough, five paragraphs later in ch17, the extremism is obliged to unravel: her indifference to the danger was beginning to fail her already.

Chapter 26 is the biggest example so far, of Fanny being funny. I mean the extent of her anxieties, such as longing to know which might be least valuable (not just wishing, but longing) and being in great astonishment and confusion. I'm not the only one who finds Fanny's flusteredness cute: Miss Crawford thought she had never seen a prettier consciousness.

Chapter 27 has more of the same: Edmund smiles and says "your thanks are far beyond the occasion", and our heroine goes to another extreme with Upon such expressions of affection Fanny could have lived an hour without saying another word. Awww! :-)