@
kelemvor - have you considered the optional metadata source plugins, such as the one I mentioned -- Goodreads. You install them via Preference->Plugins. Have a look in the
Index of plugins
When calibre adds books to a library it can get metadata in two ways, from the file name or from the book itself, it's controlled by Preferences Add Books. If your books are already in series folders then many bulk rename utilities have the functionality to inject the parent folder name into the file names.
BR