Yeah totally get what you are saying.
It is exactly this part that I'm trying to broaden the most.
...scenarios that get the candidate to stop and think before they speak and to use their experience and technical knowledge to come up with solutions
The rest of the questions as you mentioned are either right or wrong. I have quite a few of those to ask, but I am always trying to work on getting more.
People talk, and it is easy for one crew member to tell another one what I have asked during our flight, which defeats the purpose of teaching/questioning the next crew member.