One naive way to do this would be to create ligature pairs for difficult pairs (mi, lm, etc). But instead, they seem to be selecting character alternates that fill the fixed width differently based on their surroundings.
I feel at least partially the same about fancy ligatures; we could just use the actual characters in source code, Unicode is widely supported. Raku does that, but it would need better typesetting (with variable-width fonts) to really shine.
It might be ok but there is a reason why type designers make every character to be the same and try to balance everything including spacing.
Monospaced fonts designs are dictated exactly by that limit of fixed character+fixed space.
But maybe the “healing” might not be verydistracting.