Should work now. I had some bad import statements that weren't throwing exceptions for me, and I can't figure out why. Maybe my IDE (PyCharm) was secretly tweaking my PYTHONPATH or something. Now the references should work. I also have no idea which copy of pyglet was being loaded, so now it's explicitly running the one in the game's "dependencies" folder, and it should print something to the shell that says so.
By the way, if you want to see a simpler test that still fails, just run program/sprite_test.py instead of running the whole game.
To Tuturto's comment (which just came in as I hit 'post'), I can see that the conversion from 2 to 3 failed. I replaced the pyglet library with one from my older game which I had painstakingly converted by hand. The problem still occurs. Maybe I should try the pip method instead...
I'm developing and testing on Windows, so I would be curious to see if this works for anybody on a Mac or Linux system.