The appointed representative of the sponsor does not automatically make him a representative of the sponsored person. So if you did not appoint one, CEM will communicate with you directly. You and your sponsor are separate applicants... your sponsor for the sponsorship application, and you for permanent residence application.
After approval of the sponsorship, transaction will shift between you and CEM for the PPR and other documents they may require. Beforehand, it was between CIC and your sponsor. The e-cas of the sponsor will show "decision made".
It is really hard to tell where the bottleneck is unless you are sure that CEM has already received the advice from CIC. What is sure is that they have a timetable of some 10 months (pls chk this from website) although in many cases last year, much much sooner than that.
The additional documents such as Appendix A and additional information are very simple, you don't have to worry about that. Most of the info will be copied from those previously submitted. it is very important though, that you have copies of what your sponsor submitted so that you do not run into conflicting statements.