[jecilop]

As noted, the original structure cannot be changed for Calibre management files.
However, you can Save to Disk using a custom file name setup.
Prefs/Saving Books to Disk/Save Template field... here is mine:

{author} -{series} {series_index:||-}{#series2}{#series2_index:||-}{#series3}{#series3_index:||-} {title} {#words:,d|(|wds}{#time:|_|hrAvgRd)}{#audiotime:|( |audiobk)}

You can delete what you don't use. Delete the entire group that starts and ends with {} or modify as desired. If you don't have the custom # fields, you can either easily omit them or let them be. They will not show up if the info doesn't exist.

I use my own ebook reader on a tablet and prefer to know all of this info when picking a book so I save a "reading list" like this via Save to Disk that ends up on my tablet and makes browsing files perfect.