This is an interesting topic, and though I saw this early, I wanted to wait to post anything because I prefer to let discussions like this happen without author intervention, at least not immediately.
I do I like talking about topics like this, though. Humor is such a curiously subjective thing. There are people who just don't get Pratchett, whom I find the funniest thing ever. Conversely, I don't generally like stand up comedians, and actively dislike some of the comedies that people on reddit love. There are people who tell me that my Mat scenes in WoT are the funniest they've read in the series; there are others who consider them absolute duds.
Humor is more subjective than what we find heroic, tragic, or even beautiful. It also depends a great deal on audience buy-in and mood. This makes comedy one of the trickiest things to do in a book, because some people are just going to hate what you do. My approach has generally been a kind of shotgun blast--I try to include multiple different kinds of humor, stylized to the individual character. That way, if you don't find the humor itself funny, you at least learn what the character finds funny--and learn something about them.
In Stormlight, my personal favorite is the bridge crew humor, as it is distinctly character driven. Syl's humor is a different flavor, based on innocence mixed with sarcasm. Wit is another style entirely, though I usually only let him really go when he meets someone he dislikes strongly. I have to be careful, as he's one of the few characters I allow to stray into the vulgar, and letting him go too far risks letting such things overshadow the rest of the book.
Shallan's humor is based upon regency "women sit in a circle and trade witty comments" humor, of which Jane Austen was a master. Much of what the OP said in his post is correct--Shallan's fault is that she over-extends. She uses the humor as a coping mechanism, and to her, it doesn't matter if it's actually funny so long as she's stretching toward something more lighthearted than her terrible past. She tries very hard to prove herself. And she fails. Often.
However, her type of "wit" is to exemplify what Vorin lighteyed women consider to be amusing or diverting. And there are people who genuinely find that kind of thing to be a blast--though Shallan isn't exactly the best at it yet. (She's not terrible either, mind you. If you don't smile at some of the things she says, it's likely this isn't your type of humor, which is just fine. Hopefully, there will be other things in the books that make you smile.)
Though, that said, I'd love to read passages from other fantasy novels that people on reddit find to be actually laugh-out-loud funny. I know which ones I personally like, but it would be useful for me to see what you're liking. Feel free to PM them to me or to post them here.