Do you still have CEP?
I use CEP inside of Sonar for that type of editing all the time, I just select the track that needs editing, then click on "tools" on the top of Sonar, then click on Cool Edit Pro, and the selected track opens up in CEP, after editing, save the waveform, and when you close CEP, Sonar will say that the track has changed, and ask if you want to reload it, hit yes and you're done.