The C code can do anything at this point. The remaining work is to crawl through Ghidra to find interesting addresses to read/write to and useful functions to call to affect the game engine. That entails some combination of reading through function and variable names, setting breakpoints in the Dolphin debugger to check values, and writing the mod code and testing if it does what I expect.
There was Mac hardware that was only used for testing Pixar games; the testers there are the ones that told me the story.
Also I remember now some tester made a Redman/Methodman music video with video clips from the first game and was of course fired.
Unsolicited oral history of the Incredibles games I guess.