“Sliders and as it happens feedback” could probably be built in Grasshopper.
or -
What I do for fairing/smoothing curves is to apply Smooth or Fiar, look at the result, and if I don’t like the result use Undo to backup. I also use the right mouse button to repeat the last repeatable command. So Smooth with a small value of the smooth parameter, look at the result, if more smoothing is needed then right mouse button and click on the dialog box, look at the result, etc. until the curve has been smoothed enough. If I go too far then Undo.
Curves can also be smoothed/;faired with more control by turning on the curvature comb for the curve and then moving control points. Takes some time and patience though.