It's not exactly a wrapper, since you presumably still use the generated NN in LuaJIT. AI isn't my field, but it seems like a useful tool - actually setting up a complex neural network seems to be a lot of grunt work, comparatively speaking. There's probably a place for a tool that nicely abstracts over that part of the process.
This is a great service actually. Visualizing network architectures is good for teaching and discussing things. I use json in deeplearning4j and it's crazy hard to keep track of all the possible combinations of nets so it gets messy quick.