Finally, with the help of my brother, I managed to fix the categories. If you are about to ask what was wrong, I’ll tell you. The nesting was missing. All categories were in the flat list, sorted alphabetically, even though that made a little sense. Now you can everything as I intended iit to be.
I have also opened a number of new categories (such as all those programming languages) and rearranged some old ones (such as Wishlist going under Personal) without announcements. I generally try to keep you informed, but there are often these small things which aren’t worth a post on their own.