From the experts:
While we long dismissed Liesl as being stuck in the Alps with Heidi, the Nameberry community has forced us to reconsider. Yes, like Heidi, Liesl is an old German nickname-name that has never quite moved beyond its Alpine image. But the same thing might have been said of Elsa a few years ago, and many other names that once seemed inextricably tied to their countries of origin -- think Enzo and Saoirse and Freya and Soren. So c'mon down, Liesl, and join the multicultural gang of names prime for picking the world over. Many people associate the name with Liesl von Trapp, the eldest daughter in The Sound of Music>, who is "Sixteen Going on Seventeen", as her song famously says.