Hi @Giorgio_Gionni,
if you use mp4 as a file container (".m4a" files, AAC and ALAC) then I’d recommend to use a tagger which supports the respective iTunes mappings for WORK and PART.
Yate, as proposed by @John_V, will do this out of the box. It calls the respective fields “Work Name”, “Movement Name”, “Movement Number” and “Movement Count”. Roon is able to read those and will map it back to the WORK and PART values.
The (maybe confusing) mapping table of YATE:
https://2manyrobots.com/YateResources/InAppHelp/English.lproj/pgs/FrameMappingTable.html