Actually, it's not nonsense. Water very often appears in the bottom right corner. By the way, when we were still playing on CM (around 2008), I wrote about using a Shrine of the Ages in the corner of the map, but everyone just laughed.
I called it nonsense - the statement: "by the way, there is water on absolutely any random map."
Added after 9 minutes
Didn't you notice that when you open the map, the bottom right corner is darkened every time? ))) and there's always a water cell there...