If you need to correct an entry, you can go to maps.google.com, and right-click anywhere on the map and it will give you latitude and longitude in a context menu. If you click on that coordinate in the menu, it will copy that coordinate to your clipboard. Then you can manually enter that coordinate via the iNaturalist website’s Edit Observation feature.
Hope that helps!
Edit:
Oy, I am too tired, I had to re-read your post like three times. If you’re talking about correcting other people’s observations, I imagine they would have to do this themselves. I’m new to iNat myself, but the best thing you can probably do for past observations is comment and ask users to fix them. Unless you’re actually taking a team out to do observations, then maybe bring a handheld GPS device with you?
I see what you’re saying though, I looked up the same location and it’s plotted in the dead center of empty land. Maybe try clicking “Report a map error” in the bottom right hand (if you haven’t already).