Follow up: Rented speakers from local AV shop. Told the venue to take back their sound bar.
Then a few minutes ago, I walked by an open door near the banquet room - full of gear. Speakers, wireless mics, mixers. Exactly what I was told they had in planning emails. I’d say the employee helping us set up didn’t know that existed, except the sound bar was sitting right there.
I’m so annoyed. All worked out fine in the end but the frustration and running around to make it happen was a pain!