I've thought about this more and have concluded that fancy handling to let the user do such-and-such with a given non-combat if they happen to encounter it while automating adventures in an area is useless, given how people will actually play in Dreadsylvania.
Everybody I know who is seriously adventuring in Dreadsylvania sees (saw) getting a complete set of non-combat shortcuts (using ghost pencils) as a top priority. Once that is accomplished, they know exactly how they want to use the non-combats in a given instance - and they execute exactly that plan, either manually in the Browser via taking the shortcuts on the Dreadsylvania map, or via a script. For such a player, it makes absolutely no sense to say "I know exactly what I want to do with the non-combats, but I'm going to simply adventure in the zone, and if I happen to stumble across one of the noncombats by accident, I'll do that, but if I don't happen to find it, no big deal."
No player with access to all shortcuts behaves like that. Such players want to use the noncombats as desired at the time of their choice and then, when automating, skip the noncombats when they stumble across them. They want option "6".
Players that are still accumulating shortcuts will either want to see the noncombats when they stumble across them - option "0" - or, perhaps, will want to automatically use a ghost pencil (if they have one and have not learned the noncombat yet) - option "5".
Players that are completely casual and are simply running turns with no regard to accumulating shortcuts (are there such players? If so, why?) are either playing in the browser, would like to see noncombats as they appear (option "0"), or really don't care about the noncombats and will skip them (option "6").
I've never met a player who doesn't have the shortcuts and doesn't want to get them, wants to automate adventuring in the dungeon, but has some complicated ordering of what sort of prize they want to get from each noncombat. I don't care to spend a lot of time coding up stuff to cater to such a mythical player.
Now, we could set up all of the noncombats to be configurable via the GUI to go get such-and-such a prize - but since some of the prizes are limited, you can end up getting thrown right back into the same non-combat again if the choice is not available. That will cause a loop, and we'll have the same "protect me from setting up an infinite loop of choices via the GUI" that we have with the Castle choices.
If somebody chooses to set the choices via the CLI - or via a script - they can end up in that situation. In that case, they had better be running a script which will handle the choices for them and recognize when KoL rejects one - in which case, that script could presumably encode exactly the "do action A, or B, if A is not available, or C otherwise" logic they might want.
In summary, the current three GUI choices - "show in browser", "use a ghost pencil, if appropriate, else skip", and "skip adventure" are all that we need to officially support, in my opinion. Anything more complicated should and could be handled in a script.
Given that, I removed the custom dropdowns I had coded to provide those sparse choices and replaced them with automatically generated choices using my newly implemented sparse choice mechanism.
Since we have good spoilers and GUI-configurable top-level choices, I'm declaring this to be Implemented.