I'm playing XL mod and I know that VH did not mean for some units to disappear in High and Late eras. It might be that some of these were meant to carry over into the high era at least. VH is drawing up some very early plans for a new patch to XL, so drop him a line with anything like this so he can make the changes if needs be. He won't have had the time to test out all the new factions and units so small info like this would be useful I'm sure.