It is one of the most awesome puzzles. I didn't know and I think I took at least 5 attempts to crack it. But everytime, I got caught by the guard. Didn't try passing I highly recommend solving the puzzle rather than 'exploiting the going-to-be-betrothed'
Do I understand your post correctly: You didn‘t have to reach the gate and it still worked? If that‘s the case I‘ll move your post to our technical section. It would be something you can report here: https://www.playgwent.com/en/contact-support