Thanks so much for giving it a try! I really appreciate your thoughts and feedback, I will definitely take that into consideration. The Quest is one of the aspects I'm most interested in getting feedback on because it is currently one of the loosest chapters, and yeah, right at that intersection of historical knights vs. folklore knights. (Pardon me if this is long, and zero pressure to keep playing if you reached the end of your fun, but if you'd like to keep going I had some ideas.)
On the mechanics side, rather than treat the Challenge card & prompt as the beginning of the scene and then have the rest of the scene be open-ended, I would try treating the Challenge card as the climax of the scene, and the Knight's draw/Squire's roll as the resolution that moves us to the next scene. (The establishing detail can show up anywhere in the scene.)
It's a little bit reverse engineering: when I draw the card, I find out the type of challenge that will be the main climax of the scene, so I go back and set up just enough to connect the dots from the previous scene to a challenge that fits the card and the detail. So when the challenge card is resolved (by drawing the knight's card/rolling the squire's dice), the scene should be ready to resolve in success or failure, and transition to the next scene. So hopefully, in the Acts, I'm always steering towards the next challenge, and it limits how often I feel like I don't know where to go next.
On the story side, I do recommend taking big mythic swings in the Quest. In some ways the player does have to make up more stuff, but it's ok if that stuff feels a little simple and dream-logic-y. Knight quest stories are full of weirdos who want nothing more than to wear disguises and test the chivalry of strangers; they don't really even need a reason. The test the knight faces on the quest can be a really literal, intentional test, like the classic Gawain and the Green Knight "come let me cut off your head or else you're a coward" tests, or more realistic "you are in a foreign land, try not to start a war by accident by breaking an unfamiliar custom."
It's also worth saying: scenes can be Very Quick. A successful scene might be as simple as a few visual shots of the knight hearing tempting voices, clutching a holy symbol, and riding on past with determination. That's a perfectly good scene! It's ok to think of it as a scene in a montage more than a long dramatic scene; sometimes it's easier to color in a smaller picture. If it feels like you've already resolved the scene's challenge card and aren't sure where to go next, it may just be time to cut to the next scene.
I hope this is not too much of an essay! If you found any parts of it more/less helpful I'd be glad to hear as it could help me edit the next edition. And/or if you'd like to, feel free to share more about where you got stuck and I'd be happy to brainstorm a way forward. Thank you again!