I use a combo of iTunes and MediaMonkey to update the mp3 metadata and add album art.  Both does a really good job filling in the missing data.

Thanks,

Lance

https://www.mp3tag.de/en/download.html

I have been using it for a number years for managing flac files and am now using it for Music Videos too.
It can be used to determine the tags based on the file names and you can also rename the file based on the tags. 

It has the ability to process an single file or an entire folder.

This is useful for the Music Videos.

After selecting a file use Alt-2 and paste this into the 

%artist% - %title%

Its pretty powerful in a single tool and it's donationware so you don't have to pay to use it. 

https://www.jtclipper.eu/thegodfather/