I have now got a crude implementation of the Flocoder Flip program written using Flex and Bison. It can take a Flocoder file from the MUSS sources and extract what I hope is compilable MUSL code. The code is on GitHub.
I am not 100% sure that the code is valid as I have taken a very naïve approach to the code generation stage. Every BOX except the start box is labelled, and every BOX ends with a jump to the next box in the FLOW sequence. It does not attempt to merge consecutive BOXes.
However, I am hoping that this is enough to take the original Flocoder source for Flip and turn that into MUSL that I can then compile. The next step, which I have just started, is to create a MUSL to C compiler that will generate C from the Flocoder source for Flip, so I can get a version of Flip working in C. If I can do that then I should be able to process the Flocoder files using the proper code for Flip and compiling those to C as well.