Does mp3tag embed ID3 metadata tags?

It is useless to discuss this theoretically without the possibility to have a look at the original data.
You have to try.
There is an undo-function in the edit menu that you may use if you have not achieved what you wanted.
What makes me suspicious is that although thread /t/14885/1 ended in July 2013 it looks as though nothing has changed ever since. And this makes it very hard for me to help.