When I started GlotPress, one of its goals was to be a sandbox for ideas, which could eventually land in WordPress. Some of the experiments made it depart a little from the (Word|Back)Press code structure. Which can be a little bit for new-coming GlotPress contributors.
That’s why I started writing a HACKING file. It’s not complete, but it’s a start.
If you are developer, I would appreciate if you have a look and tell me if it made the architecture more clear. Or if it helped you find where some part of the code lives its happy life.