Right now I started to tweak the library in .cargo, but root directory still works.. How can I change the library and tweak it so tahat my root sees the changes?
Libraries are only compiled once and the result of the compilation process is cached (this is the reason why don't don't have to wait for every dependency to compile everytime you run your project). Try removing cargo.lock, although I don't know how good of an idea this is. The ideal solution would be for you to have a fork of that library and then taking that fork as a dependency for your project instead of the original library.
.cargo are not meant to be edited by hand. See the documentation on overriding dependencies for ways to build against a modified copy of a library.
Thanks. I was able to set it up locally and tweak