This is just one view/page of a very simple old-school admin console web UI. Yes it supports multiple hubs in the same way as the rest of the extension, but only show one hub’s buttons at a time. You can select which from another place in the UI.
The main purpose of this UI is just to provide a means of dealing with some run time or configuration issues that some people have experienced without depending upon correct pairing with Roon, which can sometimes be a blocker to resolving what would otherwise be easily resolvable issues. Statically listing assigned button is something that was very easy to add. Dynamic access to Roon state however would defeat its purpose as primarily a simple recovery tool with minimal dependencies.
A full Roon web UI is however also in development, but is still some way off due to various distractions 
Adam