If you want to treat the contents of fields then I would recommend actions or in some cases Convert>Tag-Tag.
As you have gathered from the linked thread there are apparently export scripts. I would also count action groups and web source scripts to have a script-like character. But none of them can be called externally.
I was puzzled that you
AFAI understand scripts, you have to call the script interpreter somehow and tell it to execute a script. One way would be to call the program and the script with a command line instruction. But there is no such call for MP3tag.
Right now it would be nice if you could either show us the script that would do what you intend but fails because the GUI has allegedly failed or describe/show the real problem.
See also here: