Hi David!
There's no need to use the Special Edition presets or matrices. For the piano you can use your Bosendorfer Imperial and for the Organ you can use the Konzerthaus Organ presets. Just take care to use the according programs of the VE Special Edition sound set on the Sibelius Manual Sound Sets page. It is also important to use the right Sibelius instruments in your score (Piano, Organ [Manuals], Organ [Pedals]).
Can you hear a sound when you press the keys on the virtual keyboard with your mouse?
Best,
Andi
Vienna Symphonic Library