"In a fine restaurant" sounds much better and is much more common than "In a refined restaurant". It is also a more accurate translation of "Im feinen Restaurant". Additionally, when one mentions a fine restaurant, it is implied that it is somewhat, if not very, fancy.
I don't think it should have been changed.
Considering the meaning of the poem I find "people" correct. It could also read "guests" or "they". Why, Lila, do you think that people in not right?
If nothing speaks against it, I would prefer "people" or "they".
Minny