CSE is when you contact Immigration Canada using the webform to update your application, or asking for updates....I am not really sure what it stands for but that's what it is.
It can help sometimes....I have raised 3 CSEs, the 1st 2 went pretty much ignored (though I received the standard answer: we are working on your application etc) but the third one seemed to call their attention since I mentioned I have been waiting for 11 months already. The reply mentioned that the officer had contacted my visa office to ask why was my application taking so long, and to wait until the beginning of March to give them some time to reply before contacting them again
So i keeping my fingers crossed to hear some good news beginning of March