SOLVED - obvious alternate approach was pointed out to me.
I use MP3TAG daily to organize new music and VIDEO acquisitions. I employ several file-naming schemes to organize my media e.g. Rock albums are named and organized very differently (by artist) than Dance-oriented DJ tracks (by Label and sub-Genre), and Videos have an entirely different scheme.
MP3TAG handles them all beautifully. However, selection of WHICH SPECIFIC "Convert Tag to Filename" format to use is an explicitly UI driven process, which is a constant source of frustration. I have many Multi-step actions, and also use a Stream Deck with actions assigned to buttons, which is super efficient. However, if I neglect to EXPLICITLY change the Tag>Filename format by hand before using any of my actions, it can mess things up very quickly. To mitigate this, I need some kind of mechanism to ensure that the correct format string is selected as part of the automated steps.
I am not prescribing any specific mechanism to do this, only that some method would be extremely useful. Perhaps a method for assigning shortcuts, similar to Actions, might work, or numbers, or names, it doesn't really matter what it is, as long as it is specific and can be part of an automation strategy and not involve the UI and a mouse...
Let me know if this is unclear, and many thanks for the amazing and irreplaceable MP3TAG!