...this game's code isn't that complicated like you are making it out to be. There's literally nothing else to read. End of story.
I don't want to know how long you need to build the gui alone (not the graphic/pictures). And if there really was a lot more planned, then the code should have been prepared to handle more general additions. If you want, you can google the code to build an advanced calculator, you will be surprised how much code is needed in some functions. Or if you have some time, you could add to the CC-mod and implement what you think would be nice. We would all be really happy about your few weeks of work or you are learning that we are really lucky that some proficient people are investing a lot of time.
In the
best case scenario, the game was written like the framework of rpgmaker was meant to be used. If the code is good to read (good variable names) you may be able to make small changes without causing bugs or confusing the real programmer what is happening if you are adding in the wrong place. I am quite sure that the programmer has some sort of his own framework and if you don't know about it you are fucking up whatever logic should make editing easier.
If you don't know much about the theory of programming/informatik you can be really confused about how the code works together.
And everyone that has seen programs from other people will probably know what happens if you have not the
best-case scenario. Maybe you have heard of the term of "script-kiddie", it means there is a huge difference between doing some basic work and really understanding what happens and what is possible.
@CDPR bashing:
Most companies are run by managers or have advisors that are only interested in making money and they have no interest in making a good game. If a big studio has learned its lesson and has the freedom to make its own decisions, then we players have won a lot. I think you can be angry with a lot of people who see the problems but are only chasing money.
I hope I could give more understanding/perspective to you. Thanks for your time reading.