I doubt people is willing to do your request for free. I would recommend you to check Services board to see any developer who're experienced with both C and Python. But why don't you just use the tool as it is? You just need to compile it (if you're linux user) or use compiled windows version (https://github.com/WanderingPhilosopher/Windows-KeySubtractor/releases/tag/v1.0).
I don't feel any trust issues. Since I don't know the C language, I can't change it according to my own opinion. I know a little Python language and if there is a Python version of it, I would like to realize a few of my ideas on it.