My intention is to rapidly input comma-delimitered genres in the single genre tag space without having to repeatedly type the same words. The mp3tag program offers a dropdown yet it's unsurprisingly of little use when anything that's not a "\"'d is a single genre/word. Nevertheless, I understand that multiple tags are not universally supported by all softwares and formats and comma separation works for my needs.
The goal is to come-up with an easier way to quickly input genres without having to retype words. Although I could - as an idea - utilise text expansion (eg. Better Touch Tool) to convert shorthand into words and commas, I do wish to know if mp3tag can offer workflows I'm unaware of. For example, I believe there may be a way to script multiple tags (after utilising "\") back into a single comma-delimetered field when ready to save edits; that way, the genres dropdown and custom genres section aren't a useless mess. It's not the best idea, and neither am I well-versed in mp3tag scripting, yet I hope my goal is clearer.
P.S Using mp3tag Mac