One of the most important features is missing, or I cannot find it. They are lyrics
Where are you missing lyrics? In the files? In the display? in the web sources?
Mp3tag can handle the usual text lyrics as UNSYNCEDLYRICS.
The synchronized lyrics - SYLT - the ones with timestamps in front of the text lines - are currently not supported by Mp3tag.
This is the table with all supported tags in all the different music formats:
On software , so we can add lyris text ans save that info
If I may chime in, this could possibly be added via the LRCLib API, which does support both line synced and plain lyrics. I currently am using Chronograph to do this, but due to a bug, I am having to do things manually with it.
Details for the API can be found here if needed: LRCLib API Documentation