How to edit Minecraft's base files?

Please help with editing Minecraft's base files.

I was wondering if I could edit those files (like GuiMainMenu.java) throught ClientBase.
If there'se a way let me know it, if there's no way please make it :)

Basically you cannot use the settings system with the script system

This is a newbie question, I know, but as far as setting this up so that it can be used and compiled into a .jar file, I'm completely lost. Would like to learn how to do this so I can actually start work on using this.

It fails at Task fixMcSources

with this error:

Task :fixMcSources FAILED

FAILURE: Build failed with an exception.

• What went wrong:
  Execution failed for task ':fixMcSources'.

com.cloudbees.diff.PatchException: Cannot find hunk target

i am getting this error when i run the command gradlew setupDecompWorkspace eclipse build:
> Task :compileJava FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Could not resolve all files for configuration ':forgeGradleMc'.
> Could not find forgeSrc.jar (net.minecraftforge:forgeSrc:1.8.9-11.15.1.1722).
Searched in the following locations:
http://files.minecraftforge.net/maven/net/minecraftforge/forgeSrc/1.8.9-11.15.1.1722/forgeSrc-1.8.9-11.15.1.1722.jar

If Its Hacked Then Its Useless...

seems like it's different from liquidbounce?

When i try to decompilee workspace for intellij idea with command: gradle setupDecompWorkspace idea genIntellijRuns build it gives me this error:
'gradle' is not recognized as an internal or external command,
operable program or batch file.

when debuging it in Intellij, it ignores the arguments
it says :

Completely ignored arguments: [-Dfml.coreMods.load, net.superblaubeere27.clientbase.injection.MixinLoader]

This is the full code of the RadioModule:
https://pastebin.com/ZvHjBsXd

I'm having issues with the TabGui, when I create a ModuleCategory and add a module under that category it won't show up on the TabGui and it only displays 3 of the categories, Any way to fix this? I'm kind of new to programming in Java.

When I try to create or play a world it stucks at loading world , building terrain.
Here is my latest log:
latest.log

I compile it with gradle, the build is successful and the client runs, however its just regular minecraft with forge. There are obviously mixins but they don't seem to do anything to the game. Is there a specific launch option I am missing or is this an issue?