If I cast an enchantment on a stack, I get to choose which unit gets the enchantment.  Great!  However, the selection indicator just turns the circle around the unit yellow.  My sovereign's circle always seems to be yellow, so the only way to tell whether he/she's selected is to figure out which shade of yellow means "selected"...

I suggest changing the background of the whole rectangular tile containing the unit portrait, or alternatively, displaying some unambiguous annotation (say, a checkbox).