Hi - Off topic from the iPad Pro specifically, but some there is some conversations about this: Yes, I have made my iPad with unrealBook app, send MIDI commands to call up Registrations on my Tyros5. I have a postings around somewhere on what I did. Someone else (can't remember his name) had found the "raw" MIDI codes needed to make it work; I made up a spreadsheet (Excel) where I organized all my registration files, registrations, and the MIDI codes (in Hex) needed to make it work. It works GREAT, and I really rely on it now, as a quicker way to get ready to play a song. It works esp. well for requests - I can just do a 2-second 'search' in unrealBook, tap on the song, then instantly start playing it on my Tyros.

If anyone wants help on this (for Tyros especially), and you can't find my postings, send me a note and I can try to help. I can also send my MIDI registration spreadsheet to anyone that wants to see what I did ...
It did take a LOT of work to set it all up, but it was worth it to me ...
Jim