You can have a Live Arranger Mode button on the Plugin Standalone.
You just need to add other section colors to wok with a multi style or to create custom track sections, like with just one instrument playing.
more bars than 255 for Arranger mode,
more 4 bar endings with a color part marker
midi input chord detection and keyswitch settings
midi input synth option for right hand notes
With the "Save State" this is good to allow users to make up their unique Style/key for the Live Arranger, solo tracks can be muted if not needed.
I think this is something that can be done now with not much work.
I have shown it all working in that terrible Reaper, as Reaper detected a midi chord input it went to a region that corresponded with that chord name and part color in the Plugin smoothly and seamlessly and just looped that region until a new chord was entered.