Hi.
I took a peek into the Roland site to see and read about it.
There is Style Converter software for Windows (and macOS) downloadable.
HEREQuote:
"
E-X Style Converter can convert MIDI file to STY file which is the style file format of Roland E-X series. Tone parameters, Chord transition rules, One Touch Setting (O.T.S.) are assignable as useful function of this software."
Maybe other Roland arranger models will read the converted files as well? That would be cool ..... 😎