What really happens at the end of Figaro?
The actions on the stage are generally pretty clear. The count mistakes his wife for Susanna and gives her a ring. In contrast Figaro guesses pretty quickly that Susanna is not really the countess.
I believe that the ending only makes sense if the count and countess enter the summer house together where they stay for a sufficient time to allow for some serious love making. And then when the countess emerges for the count's ultimate humiliation it must be from the summer house still dressed as Susanna. The count feels as he does because he realizes he has just happily made love to his own wife.
Instead it's garbled. Yes, she shows him the ring, but those kinds of things are hard to see on stage. She changes her clothes, making it clear that she's been in the palace and not in the summer house.