If you want to dive deeper into Cakewalk's synths Simon Cann's "Cakewalk Synthesizers: From Presets to Power user" is still a good reference even if it's from 2009. He's even made a (downloadable) upgrade for Zeta2 that came after the book, otherwise I think it pretty much covers what you get with Sonar X1/X2.
 
http://noisesculpture.com/cakewalk-synthesizers