Oh, I see now that one of the DL solutions reads: Acel
that restaurant s-a închis acum.
Is the "s" there in "s-a" because închide is reflexive (i.e. a se închide)?
Yes, it is reflexive. Both variants are used:
Shouldn't the correct translation be: restaurantul ăla a închis acum?
It seems that the solution provided by DL (i.e. Restaurantul ăla e închis acum) should instead translate to: That restaurant IS closed now.