Hey Davin, thank you for the answer. My apologies if my question touched somebody’s feelings. 
Just I understand that Jupyter/Python side integration was created 1,5 years ago with Knime 3.7, and it does not seem too mature 19 months later, considering that there is no documentation (or I just am really bad at googling) and from forums it seems that feature is hardly used by anybody. Really, only way I could find out that there is no property for flow variables container input, was just listing all the wf object’s parameters from python side.
I read about Jupyter integration just today in KNIME newsletter email, so I immediately went and checked how it works. Do not have a real use case for now, though. Will check the features requesting part in github.