As far as I’m concerned, the problem with contrast in linear interpolation is currently addressed with adding an intermediate master or tuning the generated instances. My solution offers two possible advantages: (1) it can be easily automated, (2) contrast between horizontal and vertical strokes can grow smoothly within the family.
The problem with diagonals is also present (though less visible) in traditional linear interpolation. It can usually be addressed with fine-tuning the design of masters.
