"Liliane" is a beautiful name. It also, incidentally, does not make you sound as if you are hedging your bets in case you need at some point to take up the oldest profession or any kind of surrogate for the oldest profession.
Or, you know, twelve.
I realize that she started making films when rather young and that "Liliane Sobieski" does give off a sort of "I want to be foreign and exotic and Catherine Deneuve" vibe, but I don't care. All sorts of young actresses have not only grown-up but actually totally wackadoo names. Abigail Breslin? What is this, The Crucible? Dakota Fanning? Seriously? What's next? Illinois Carpenter? We named the dog Illinois!
If your name is Liliane and you are beautiful, do not sell yourself short! Gross.