Use communication. Its very effective!
Agreed, this would actually be insanely useful! You could use the small buttons in the rally point for incoming attacks for this (say clicking green for fake/not important, orange for possibly dangerous (ram/cat) and red for definitely dangerous (cat)) and connect clicking those to the kingdom incoming attack window and/or the map. This helps a bit against those who like sending out attacks stupidly, as in, just sending loads of fakes.
But that doesnt work when you have multiple inconming atts which may be partly fake and partly not.
They'd need to change the UI a bit, yes
Hello there 
yes, exactly, it is already adjustable for yourself, giving this kind of information to all players within the kingdom is a great suggestion UX will thinks of something.
