Real Time Control Point Accuracy Feedback
Most times I am Georeferencing I wonder, is the control point I'm about to add accurate. It would be wonderful to be able to instantly see if it was after I add it. Three specific suggestions.
In the Coordinates Pane, prominently show an Average Error score. That way after a point is added you can see if the score goes up or down.
In the Transformation tab of the pane show an Average Error score foe each of the transformation types you can select. That way you know which one is best to select.
If you add a Control Point and would appear as Bold Red in the pane, then show an "Are you sure" pop up dialog (or similar affordance) that warns the user and prompts them to click, "Yes" to proceed.
Note that #3 would not be needed if the Coordinates Sidebar improvement were implemented - https://georeferencer.uservoice.com/forums/41573-georeferencer/suggestions/33068386-coordinates-sidebar-on-side-by-side-and-overlay-la
This is a great idea, we will definitely consider implementing this feature, but it is not a priority at this moment.