Julia Alvarez, 74, has been thinking a lot about what it means to be an elder. In her latest novel, “The Cemetery of Untold Stories,” the central character — a celebrated Dominican American author, like her creator — regards her literary reputation with skepticism: “The glow of celebrity now tinged with nostalgia might keep the fan fires going, but Alma didn’t want anyone’s condescension or pity. The time had come to stop beating herself up for not being able to finish anything. She was trying to hold on to the literary version of good looks, the plastic surgeries of astute agents and editors nipping and tucking the flagging work.”