Hello, Ive discovered some things you can add to your mod to make it a little more detailed..
If you open up the interface_textures.kfs there you will see two images of each of the companions, one with a white background, one normal for example, for Agvares there are face_demon_Agvares.png and HeroItem_partner_Agvares.png, replace BOTH those images with yours (Make sure one has no background), what this will do is not only will you see the new image in the chr screen, but when you talk to the companion that image will change as well..
The second thing you can do is open up the eng_actors.lng file and find both instances of each companion, and change the names to the new ones, what this will do is when you click on them to speak with them, there new name (along with there new image) will show up
Below is a screenshot of what it will look like
(Note I used the debug teleport to go get her to show you)