"This is a wonderful movie sharply picturing the challenges and questions many children face during their childhood." seems okay, but let me get into the perspective of the question, you want to explain the movie's motive to be " exposing, or making people understand or bringing to light" the "challenges and questions many children face" , so this movie tries to accomplish something other than entertain the audience. It tries to create awareness among the audience, and it tries to have an impact on the society.
When you say it "pictures" it just means the plot of the movie is about "the challenges and questions", I would like to suggest " puts into perspective " the issue
"This is a wonderful movie that puts into perspective the challenges and questions many children face during their childhood."
I think "puts into perspective" emphasizes to the reader the that the movie has as deeper purpose other than entertainment.