If you need, in metronome marks:
=sign to other symbol, you can use the property
-sign between tempo values (e.g. 100-120) to, say, 100~120, you can use the property
This snippet is based on a snippet by Arnold Theresius. The original snippet create a formatter called
format-metronome-markup-approx, and the default value to
tempoEquationText in that snippet is "≈". I changed back this default to Lilypond default, and added the
tempoBetweenText property. Also, I changed the sizing of some elements, as described above.