The FA training is a minimal issue. Half an hour of "ancillary revenue training" plus a laminated placard would easily suffice. While I agree that FAs shouldn't have to become expert on all aspects of elite status benefits, FAs are the last chance to monetize extra-cost seating options.
The laminated placard would contain a simple flow-chart along with photos of elite status cards that would get the E+ seat for free. Similar to the laminated cards that help lounge attendants determine who gets admitted.