Tags - Textfile (window) is a beautiful feature in mp3tag. We need the same feature in reverse direction.
Fewer number of songs (say 10-20):
We can load songs in mp3tag. Copy tags and make conversion (language), spelling correction, etc in an external application and paste the tags back to songs in the same session.
Larger collection (100s-1000s):
We could export "tags - textfile (csv)" with "_path" and make changes and import back to mp3tag (in windows).
But unfortunately, it is not an option in mac. It is another request. I am not cross-referencing that thread here.
Right now, that way we export and import tags in/out of mp3tag has limitation.
Clipboard: is fast and efficient for fewer items.
Windows/mac: limited to one way, import only
CSV: is robust and powerful for larger items.
Windows: supports bi-directional
mac: only one-way, export is clear and import is dangerous