Alena Smith, the playwright and author, is not what comes to mind when you think of the word “tween.” For starters, she’s 34 years old. And her credentials include off-Broadway productions like The Bad Guys as well as a stint writing for the last season of Aaron Sorkin’s The Newsroom. But standing in front of an audience at BookCourt last Thursday night, Ms. Smith transformed her usually confident voice to slope upward: the question mark lilt hinting at a voice of a generation (as Ms. Smith’s fan Lena Dunham might put it) albeit one a smidge younger than her own.