Leozard

Still the same in version 20.5.550. I think they need to improve that UI. Just add a little X to the right of each list item to remove it from the list

How would a ball explode and deflate at the same time/frame?

I think we all agree there are workarounds - typical Houdini style; albeit tedious ones; but also we should agree it will be an improvement and not an impediment to the software for something of the sort to be implemented. Houdini has this reputation of making easy things hard especially for newcomers to the software.
Creating an HDA you can, then soon enough you get to start doing UI/UX work when keys accumulate of all the parameters and you have to promote them; and things like these become overhead 9That you as animator don't need to bother with especially with tight deadlines)that would be solved by my suggestion. Case in point, when doing motion graphics with MOPS nodes, you get to key lots of stuff on many different nodes - falloffs, modifiers, etc. A quick indicator of where those keys are PLUS a little window to the side in the current context you are working in of a list pane that would collect all such parameters can be a huge time saver