Like the Extra Cheats DLL, this DLL is intended to be a GZCOM-compatible library which SimCity 4 loads and provides C++-fluent modders with an interface to control game functions.
As of the last commit, the DLL is callable by SimCity 4, and the DLL can call into game functions including enabling debugging functionality (i.e. the extra cheats DLL). The COM director instance is entirely functional, and is able to subscribe to hook events like PreFrameWorkInit, PostAppInit, and the rest.
Since most of the core work is done, the rest of the effort is focused on finding other classes and interfaces to add and fixing poorly documented methods with unknown parameters.