Hi Miriam,
I'm very happy with your interest in packing the game! It would be incredible to finally give something back to the Debian community.
We tried to use only free material in the game. I understand very well your concern. Due to the complexity of the Licenses we found no adequate sound effects for the game, for example.
I talked to the responsible for the art and sound of the game, and he told me just the same problem you reported. The website allows the authors to change the songs licenses and some licenses seem to have changed.
We would like to fix this problem. We can check each song and font of the game, changing the troublesome ones.
This would take some time, though. I believe we can have a new version fixing the Licenses issue by the beginning of April.
We'd also be very interested in the suggestions you might have.