Ah, I spoke too soon!
I just tried the first one on my list, and it appears in one bundle page (but with no download button, and only a link to a 404 page), but it doesn't appear in the other page for the same bundle when I search for it.
So I guess that creator found a way to properly delete the items.
It will be interesting to see what proportion of missing items can be downloaded using the method below. :-)