Thought it did but welp... sadly, as you can see in the above images, she indeed has that shadowey grey head outline in the roster, even though she has a portrait in other places like the unit details page etc.
So I've been trying to use Project_Knight's alternate (battle/Seiros) Rhea character file from Page 150 to get Rhea to appear in her Seiros battle outfit instead of her normal robes, but it doesn't seem to be working. She still appears in her normal Archbishop robes when selected as a unit in...