Hi Richard,
In running convert.ly from version 2.26.0 on a file that compiles with 2.24.0 I get a change in name from ly:duration-length to ly:duration- moment. But the typesetting is completely different. The code concerned is a definition to allow setting the spacing in a graceAfter grace note. Here is the MWE
Could you please provide the original, working (with an older LilyPond version) state of your code before convert-ly changed it? The code is a bit opaque and doesn't seem to be written very robustly (what with the hardcoded nested 'element / 'elements selection); it would be easier to start from a working version of the code.
Lukas
