(I had a couple like that as well as a fair number where my note was something like "A checker for this challenge is now available at <link>", for challenges all over the world that I'm not likely to ever log.)
By doing it this way, caches you have written notes for and forgotten about will be seen, but you may have a too many items in your list. In your case, this seems to be challenges that you plan to perhaps log some time, even if you haven't actually signed them.
By doing it your way, everyone would start with an empty list and no one would find surprises like I did, challenges I signed a couple of years ago and turned out not to qualify for when I got home, wrote a note for and then forgot about.
I like the current model. Perhaps some people haven't actually signed all the challenges listed, but they have interacted with them somehow. In at least many cases, they are likely to be working on them even if the challenge is not actually signed. See this feature as a helpful todolist even if it may not do exactly what the heading says in your case.