Thank you for reporting this. It's actually not a bug, but it just depends on which route you take through the tech tree. It may seem a bit weird indeed, and when you choose the lower route first, you'll indeed first come across number 10 but when you take the upper route first, you'll come across number 9 first. It might have been nicer visually to place them in the same row but then you'd have to squeeze in the Sorceresses tech somewhere, so for now we'll mark this thread as "not a bug"