For my sake and the sake of transparency, I’m gonna address these one by one:
Monument Point is located within commuting distance of DC, which a little subjective research seems to pin to about 15 miles outside the city max. That gets us a radius, but a radius that stretches across two states, which means even my last ditch solution of pinning the location to the state and marking it as “Location Unclear” wouldn’t be applicable. If I could get a state or even a cardinal direction, some inferences could be made, but as it stands, it’s just barely too broad. Monument Point is located in Virginia in Arrow, which would normally be completely irrelevant, but considering that Marc Guggenheim was showrunner on Arrow, I’m tempted to make an exception for it. But, if anyone tried to fact check me on comics alone, they wouldn’t reach the same conclusion, so I’m going to pass on Monument Point for now.
Challengerville is an interesting one! Apparently there is an actual small town in Colorado named Hadley, which settles the location pretty firmly I’d suppose Now, the question is: does that make Challengerville a fictional location? For the time being, I’ll say sure, why not!
Markovia has actually been placed in several locations, all somewhat near to each other, but not near enough. Its first appearance in Batman and the Outsiders #1 places it in the southeastern portion of real-world Belgium. The Atlas of the DC Universe has it eating up the southern point of real-world Switzerland. Secret Files & Origins 2000 places it on the lower end of the Austria-Hungary border. Since there isn’t a more widely used option (even in other media, the proper location seems to be all over the place) we’ll go with the most recent information and place it in between Austria and Hungary.
I haven’t been able to find any source but for the Arrowverse that places Gorilla City in the Congo. I also can’t find any source pinning it anywhere else, so I think I’ll refrain from adding it until I can find a solid source. If anyone has one, please let me know!
Qurac provided me the very special opportunity to put my new Who’s Who omnibus to work, so thanks for that! A map from the fourth issue of the '87 updates depicts Qurac stretching along the Persian Gulf, just as you described! But, since it’s such a big and oddly shaped country, I opted to use MapHub’s polygon tool to make a general sketch of the shape rather than using a single pin. I might try to do this for other countries later, since that could be a bit more useful than the pins alone.
MapHub weirdly doesn’t account for Antarctica, but even so, Antarctica is way too general for my tastes. (I even went looking for reference images to see if there were any landmarks I could work from…in Antarctica )
Belle Reve raised a question - do remote locations deserve markers alongside cities and countries? I’m thinking in rare circumstances for the very iconic ones - Belle Reve, the Hall of Doom, the Fortress of Solitude, etc. - I’ll include them when there are details enough to pinpoint there location. That being said, for Belle Reve, I didn’t have to! Belle Reve is located in Terrebone Parish, Louisiana, so that’s what you’ll find when you look on the map!
Again, thanks so much for the suggestions and the info - it’s the number one motivation I have to update this thing! If anything else springs to mind, don’t hesitate to come back!