The only way to see what chords are used is to quick record the intro and then when you play it back the chords will show and you can write them down.
If I do this on my Tyros4, the only chord that shows in the score display when the MIDI is played back is the initial one used to trigger the style!
As a style plays, it's internal patterns do not produce any chord events that are recorded, even in an Intro or Ending which could contain chord progressions.
It appears that Chord events are only produced by chord changes detected from the keys pressed in the style section of the keyboard, but obviously when playing an Intro or Ending you only actually play one chord at the beginning of the section to actually trigger it.
If you watch the MAIN display, the currently detected chord is shown on the screen and this is what is recorded when using MIDI Quick Record on the keyboard. Start a style intro that you know contains different chords. Other than the chord used to start the style, do you see any chords from the style pattern shown on the screen? Well, that is also what is recorded in the MIDI!
As I said, this is what happens on my Tyros4. Perhaps other models are different, but I doubt it! Maybe I am doing something wrong?
As Vinciane said "This is really a neat and useful trick", and I agree that it would be - if it worked!
Regards
Ian