Wow, this is very nice work. Years ago, I was a wanna-be Flash programmer and I always tried to achieve 3Dish effects but alas, any neat effect I ever did tanked the CPU. This is what I always wished Flash could be.

I was reading the "Furnishing a Room" article. It shows a few tabs that I can not find. The Blend4Web tab is missing in the Scene, Export, and some of the other panels. Please see my attached image. I have the render setting on Blend4web and I am able to export html and json. Maybe I am missing a basic step?

By chance did you uninstall and re-install Blender? I have noticed that uninstalling Blender deletes the blender_scripts directory.

Very nice. I like it! I think Blend4web has a lot of potential to fill the web design hole left by Flash. Can clickable links be done inside Blender, or do we need an external JS file to handle that?