I don't think the reviewer was actually claiming that von Trier is depressed, he was just using that as a manner of speaking, and it's meant to be sort of amusing, I believe. He's just making a joke, pointing out that it's unexpected that the director would make something with a comedic/satirical air after his last…

I wonder which of the musical numbers in particular the reviewer thought were 'clunkers'- I really enjoyed all of the songs a lot, perhaps with the exception of 'Frozen Heart', which was just kind of boring and pointless. I did wish that they had given Kristoff his own real 'wish' song or love song or something, or…