Yamaha calls those "Registrations."

Vadim, apologies if you already tried this... But perhaps you could connect an external sequencer or DAW to your Yamaha's "MIDI Out." Access the Yamaha's MIDI menu, and configure it to send all data. Then, select a registration, and see what the MIDI / SysEx looks like. By "spying" on the internal workings of the board like this, it might tell you what kinds of messages you need to send to set the voices and FX, etc. My $.02.