I used it quite a while ago (not something you need regular like if you are careful
)
It worked for me, populating a (then) new computer with 4 Libraries.
Exported (just left all of the items ticked).
Imported (IIRC I had to create destination folders and
indicate the NEW path)
In another case, I just imported the settings (AKA Preferences)
Kovid: The Help page is awful thin
in this area (like, nothing):
https://manual.calibre-ebook.com/gui.html#library