As of 1.09n, whenever the player creates a unit design, it goes into the My Games/Elemental/Units folder. This includes all designed Units, Sovereigns, and Champions (made by using the Sovereign creator and then removing the <Sovereign> tag in the .XML file).
Now, let's say I play a game as Tarthans and I create a unit design that has a leather cuirass and a spear. Let's say I call them "City Guard" for example. In my next game, maybe I play as Mancers, but I want the same thing, a unit design with a leather cuirass and a spear, which I also call "City Guard" because in my mind, it's the same thing. Then I play as another Kingdom race, etc. Well, when I go look in the Units folder, I see three or more "City Guard.xml" files, each with some numbers after the name. It does this because the game needs a file for each race. Unfortunately, when you add in all the designs created in a game several times over, it gets to be impossible to keep track.
Here's what I propose:
When the game generates a unit .XML file, it first checks to see if a folder with the name of the race exists. If not, it creates one. The .XML file is then saved in that folder. That way, unit designs are saved in a folder for their race, and the game is able to create folders for custom races. The player then knows that if he/she plays as that race, all of the units listed in that race's folder will be available. Each of these race folders would then have an Icons sub-folder so the .PNG files get sorted as well.
There should also be a Sovereigns folder and a Champions folder.
Inside the game, add a Delete button in addition to the Retire button to the Unit Design screen. Hitting the Delete button would delete the .XML file and the .PNG file, while hitting the Retire button would remove the unit from that game but leave those files for future games. Ideally, it would be great if when the player creates a new design, the game could check the .XML files in the race folder to see if any units with identical gear exists (it would ignore facial appearance, clothes that don't affect stats, etc.). If it found a unit that had exactly the same gear, it would pop up a message box that would say, "An identically equipped unit already exists. Would you like to add it to your game?" with Yes and No buttons. This would provide a means for players to bring back previously retired units without creating duplicates.