I start calibre from a script and added some rsync stuff to the script. This means that every time I quit calibre a full timestamped snapshot of all my calibre libraries is made. This is pretty fast since the previous snapshot is "reused" and only changed files have to be updated in the new snapshot.
The scipt can be found here:
https://www.mobileread.com/forums/sh...d.php?t=244228
I still use pretty much the same script.
You can "transform" a calibre library by renaming and moving the books and creating new folders and sub folders in marvelous (to you) meaningful (to you) structures.
There is a script that can do this. It is a part of ebook-tools, rename-calibre-library.sh. You can find ebook-tools here:
https://github.com/na--/ebook-tools
Now you just have to combine what these scripts do, and you have exactly(?) what you ask for. The scripts I mention are for Linux, but I think Microsoft has added some Linux compability to Windows, so the scripts may be possible to adapt to a Windows environment. Or you can join the dark side...