Here's your Biab Live Arranger playing wma direct
https://www.dropbox.com/s/g28fd8zss4me8h8/Biab-Live-Arranger-WMA.mp4?dl=0
you just need to put it in an easy programmed crossplatform language so you don't spend half the year on Win and the other half on Mac.
It just needs to be basic without all the Biab features.
When the user loads a style it just loads all the track data for those RTs and plays the user's chord input back direct from the wma/wav source file sections that are referenced in the data.
Or you can just wait till Yamaha do it.