I have entirely re-written RenumKiCadPCB into c++ and made it into a GUI (Windows-like) program. All the source files as well as build instructions and a Windows 10 installation file (RenumKiCadPCB.msi) can be found at https://github.com/BrianAtDocumentedDesigns/RenumKiCadPCB0400
I also added a few features and fixed a number of bugs. For example, you can now rotate all reference designations on F.SlikS (or any other test field) to an arbitrary angle).
As usual, please contact firstname.lastname@example.org with bug reports or feature requests.