The source files don't open in either version that you can download of PyxelEdit on Mac.
Hi, Steven!
We've just tested it using Pyxel Edit version 0.4.95 for Mac, and the source files open correctly. Could it be that you're using the unsupported free version of Pyxel Edit? If you're using the latest version, everything should work fine.
If you come across any clues that might help us investigate further, please feel free to share them. We're happy to help!