Okay, here's what I've figured out: Cubeupload deletes anything that isn't a letter or a number. It also truncates every filename to twenty characters. This means that for games with very long names, the creator's name gets cut off at the end.
That's why I would suggest the following:
1. If we want to avoid having to edit the filenames later, the only option would be to separate the image name and the artist's name maybe like this: ImageXArtist.jpg or ImagezzzArtist.jpg.
2. Longer game titles should be shortened so that the creator's name remains at the end.
That's all I can think of off the top of my head.