Is it conceivable to only interpolate the selected nodes?
Like in this W where I only want to correct the weight of the inside diagonales.
Put the original in the background. Then after you do stuff to the outlines, select the nodes that you didn’t like to change and use the “Interpolate with Background” to move them back where they where.
That’s a good tip, Georg!
That said, the idea of allowing to apply the RMX Tuner only to the selection has been on my to-do-list for more than ten years. I was thinking about making the arch of the f wider or narrower as a use case. For the implementation, however, it’s not easy to “connect” the scaled portion and the rest to each other in the end. If the connecting points don’t have the same distance then we will need some sort of gentle stretching and bending of the contours, or possibly shifting the points along the contours, all of which which is far from trivial.