Porting open-source SW partially written in C# fully to C++

There is a SW package (under GNU GPLv3) that is mostly written in C++ and cuda but has a GUI written in C#. Unfortunately the GUI prevents the use of the SW on Linux-based systems and it also contains parts that should not be part of GUI. We are searching for a programmer that would port the C# parts to the C++ so the new SW is OS independent. The GUI does not have to be provided at all, the fully command line solution would work as well - but this could be discussed. Further, we would like to add some functionality to the code, mostly in terms of outputting some values computed during the run, and to remove some know bugs that exist there.