You MIGHT want to simply read the manual. an NTA channel HAS been added...

Quote:
from p.43 You can receive program change messages to switch divisions
of the Style, or cause program change messages to be
transmitted when you switch divisions of the Style.
You can also receive chord input from an external MIDI
keyboard.


If you are basing your info on what Roland support techs have told you, good grief! You should know better than to accept anything they tell you..!
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An arranger is just a tool. What matters is what you build with it..!