I have little information regarding your motivations for remaining an Elder with these sorts of privileges. I would imagine there is some part of you that wants this task? I'll try and peek at your back story.
Personally, I say either do the job your asked to do don't do it at all.
In fact, I would argue that if you simply make the job your own and do better than the WTS want's it done, it would have more lasting impact with people. Ditch the probing questions and instead just try to be funny and likable. Use charisma. If you ever leave the group, they will remember you more fondly. Somebody who they looked forward to hearing talk.
Those meetings are less about the beliefs than you think. Just my 2 cents.