The last error with PyTorch 0.4.1 / 1.1.0 is already clearer than the previous ones. Making progress!
This seems like some module in PyTorch isn’t supported by ONNX yet, maybe… The second last line (X = embed._backend...) in your stacktrace appears to call the backend’s Embedding module, and I have no idea what that could be and how to debug it.
I’m afraid that’s as far as I can help you  Maybe someone else had a similar problem and can comment here?