I believe you need to set the control channel to send registration,user program data....The problem though as I understand..The Yamaha arrangers as well as other brands are limited in midi data operation...I don't think it is possible to set a control channel recieve on the Tyros4..

As mentioned above you can make program changes via midi on individual channels..Try to send a midi set from the accordion to the Tyros4 ..it may receive multiple channel program changes..Although the Roland accordion may be limited to 8 midi sets...