Use GridLayout with 3 columns. First column for label, 3rd column for undo button, middle column for everything else. That means you might need a RowLayout for some clusters of controls in the middle column (ala SliderSpinner). The RowLayout might need a spacer item with fillWidth:true or similar to prevent controls from stretching way out and looking stupid. The SliderSpinners look good stretched out, but I dislike overly stretched combo boxes. When we add parameter animation, there will be a fourth column for the stopwatch button to add the parameter to the animation timeline.
Right align the label. I know some people may not like it, but it is the direction I chose and want to stay in. I want to maintain style consistency.
Regarding labels more broadly: