[Adoby]

If you find the work to be too much for you, you could hire someone to do it for you. It would be significantly less labor intensive for you.

It is good practice to fix books immediately when you add them. At the very least author and title. Otherwise there really is no point in having the books managed by Calibre.

Also note that the books stored in the Calibre library typically doesn't have the updated metadata stored in them. The updated metadata is instead stored in a separate database file metadata.db. That is one reason why it normally is a bad idea to even bother looking inside the Calibre library. Use send to device or folder or save to disc. Those books will have the updated metadata inside them.