Hi. I noticed that when I delete a mood from a custom soundset, the mood reference in the left column disappears, but its elements remain in the soundset. That causes unnecessary bloat, and makes download to the offline players bigger and slower, while not using (big) parts of it. Removing its elements by hand from the soundset after deleting a mood is a pain in the butt, as I often do not remember which elements it contained, so it becomes a painful process of elimination. Is there anything I can switch, toggle or do differently to delete moods from a soundset, together with all of ifs elements?
I agree that would be a great feature. When I add a mood to a soundset I have to be absolutely sure I like it because of that problem.
Yes, agreed. 
What about as a first step, something to at least FLAG elements that are NOT being started by any MOOD, to make it easier to see which ones are safe to delete?
That would be very helpful as a start, as that would save a lot of time figuring out which elements to delete. What would be a great add-on to that feature is the ability to select a batch of elements before hitting Delete. Currently, elements can only be selected one at a time. I understand batch selection might clash with the functionality of the right column, but maybe you could toggle that column to grey out as long as a batch selection is on screen. Anyways, just my two cents, not hindered by any coding skill whatsoever…