Menu system has difficult behavior
Navigating the menus with a pointer requires that the user hover continuously over the item they want to expand until they reach the desired menu item. If the pointer strays outside the menu, the whole expanded menu collapses and they have to start over. This is bad for people with less precise movement. It is good that one can use keyboard navigation for the menus but not all users will use a keyboard like device. This menu structure also uses the menu heads and subheads to link to pages rather being a heading that just expands a further submenu. This means you can’t use a click to hold open a submenu while you navigate to its item.