I think the trials are Gray in that she finds herself pulled between light and dark, but ultimately she chooses one! (Spoiler so I wont say which one!) This is reflected in her gray clothing throughout much of the film. In the end, she wears white or black but I won't tell you which one. So no its not lukewarm. It's very clear on good vs evil but the gray trials are the tension she feels when she's not sure which she will choose.