after a LOT of spamming jump&attack i finally climbed the 'gears' area to cross the bridge. 3 hours total, 2 yesterday, another 1 today, but yay, that's over.
Now, I got past harriet's "harriet" parry phase, and on to her bookshelf stomp phase. I died there, and on game reload, she tells me to go back and find the S section. I oblige her, and find the S section again, but on returning to her, she does not progress the quest. In fact, in my log, the quest remains checked, showing completed, but I can't ever fight her again, no matter how many times i reenter the Library and find the S section.