I felt same when I faced an issue when I tried to improve layer panel a bit some time ago. And found it seems impossible to fix the multi-click issue of gtk tree widget. Inkscape faces the same issue for its layer panel too. The Gimp does a good job here, its layer panel works very well, unfortunately it is not gtk tree widget but a customized widget.
My params widget redesign does’t intend to introduce multi-clikc soultion but trying to reduce multi-click. I would like to design an intuitive widgets for parameters since user heavily adjust parameters while building animations in Synfig Studio.
I will create an motion mockup for this widget designs latter on, so that I can present my idea in a more clear way. just be patient 