iTunes to edit the actual files in the Library

It somewhat depends on what you mean by editing the library files. The library database is a record of what has been added to the library, where it is stored, and what properties are associated with each item, along with any playlists you create. Changes to the library are made by way of the Song Info (Ctrl+i) dialog or editing playlists. If you want to make more complicated bulk changes this can be done via various scripts such as those I have at made available at https://samsoft.org.uk/iTunes/scripts.asp. You cannot directly manipulate the .itl file.

tt2

I see. iTunes doesn't check for changes made by other software. It should notice that a track has been updated if you play it. If there is a batch of tracks that need to be refreshed you might try my UpdateTagInfo script. Once iTunes knows there has been a change the files should be updated on your device at the next sync. If not they can be removed first, then added back.

tt2