Changing the compass image location in overviewerConfig.js has no effect. It seems like the file overviewer.js sets the src for the image based on the north_direction and doesn't take your custom value into consideration.
See CompassView::render function in overviewer.js ~ line 180
Hi, yes you're right, the url is ignored in overviewerConfig.js, as it's hardcoded into overviewer.js. I've removed this variable. Let us know if there is a desire to be able to specify custom compass image urls
Removed overviewerConfig.CONST.image.compass. It was unused