Hey fellow world builders, I (M37, she/her) am a historian and cartographer mapping the world my friend uses for D&D and I recently discovered a mistake that makes me question my friend group.

The friend I'm mapping for is a DM for a 5e game and has a world he's been building for years. The campaign we played in recently is set in a fictionalized version of North America with some significant changes, like a modern state equivalent to the historical Confederacy that made peace with an equivalent of the United States. I've also added some coastlines, a few mountains, and changed some lakes. Now, when I was originally sketching out this world in 2021, I followed the basic outlines of the North American continent, but I did make a couple of changes. <br><br>In North America, there is a real lake called Lake Pontchartrain that is almost due north of the city of New Orleans. In my friend's world map, he told me to replace this lake with the Mississippi River delta, so I did. At least, I thought I did. <br><br>I recently started making more detailed maps for this friend, including a map of the region in question. So, I was going back through my notes from our sessions and memory of the world, and I realized I hadn't actually been told anything was where Lake Pontchartrain is in the real world by my friend. I had assumed it was there for some reason, but as I thought more about this I started to feel really weird. <br><br>The reason I included the Mississippi River delta was because I originally thought that in the real world Lake Pontchartrain was actually a smaller offshoot of the delta, which is not true. I know that now, but looking back I feel really weird about having placed an important landmark for my friend's campaign world. Now I just feel like I may have messed up something important, but I also know I don't want to ask my friend about it. Am I just being paranoid? I want to map this campaign world for my friend, but now I just feel like I've messed up a very important part of their world. Any thoughts on this? TIA<br><br>TL;DR: I made a mistake mapping my friend's fantasy world by swapping the location of the real world Lake Pontchartrain with the Mississippi River delta and now I'm paranoid that I messed something up.