That's helpful. Thanks. I never did get up to speed with regular expressions.
I use the cutLeft and mid/substr (whatever) functions to sort out Titles that have been copied from the filename - where the filename includes track number and album ...I have to modify the action each time, and count the characters.
To strip the track numbers, or replace the full stops/periods with hyphens (like replace "12." or "12. " with "12 - The Track Title"), I use RenamerNG (free program). Much easier (perhaps even if you're familiar with the mp3tag scripts/coding, because you can perform the actions on selected files, the Trim and Replace and Insert dialogs show you what the result will be, and you can Undo if it's messed-up.)
I doubt that anything could be easier and just as powerful as the functions in MP3tag.
You can do just the same things and many more with MP3tag, with the advantage that you do not have to leave MP3tag to start an external program which probably has no options to recycle any tag data.
I would think that it would be much better to get acquainted with the powers of MP3tag and leave that promoted program of yours where it is.