As you can read within the Mp3tag export script, ... the parameter list of the $filename function shows it, ... the file to be created will be a DOS command file having the file extension ".cmd".
At end of creating the export output, then the user will be asked to execute the just created command file.
In case of the offered DOS command file will be executed, this process creates a new text file, which holds the exported text from the tagfield UNSYNCEDLYRICS in the same layout as it has been stored before within the tagfield UNSYNCEDLYRICS.
There may be no need to modify the target text file, ...
unless the USLT language ID has to be changed.
https://docs.mp3tag.de/mapping/#unsyncedlyrics
Exporting UNSYNCEDLYRICS to Individual Text Files
DD.20171003.1050.CEST