When I enter a page range for an index entry, that range 'sticks,' meaning it will be applied to all subsequent entries made by selecting a text and then clicking on the "New index entry" in the Index panel. Since the result isn't show to the user, the result is a long of wrong entries.

Fix: The page range should not default to the previous entry. It should default to the most common entry, "Current page." If you want to allow what happens now, add a "Make this range the default" check box.