I am having this problem as well. If I correct coordinates on the web site, they are not sync'd in the app. Rather than re-install the app, I have found that if I go to Settings, Applications, click on the Geocaching app, then Storage, and the Clear Data button, when I log back into the app, the corrected coordinates will appear.
I'm using Version 5.8.2, Android 7.0, Samsung SM-G930R7.