I finally found the solution to this damn graphics problem:
All civ-members will be skeletons. And you... you will be Sauron, more or less. Skeletons do all the labor, but cant learn spells... but you can bring one skeleton to a workshop and run: "Possess a body", or "Take on form", and then the skeleton will transform into a caste that is allowed for the noble position. And the noble position has the special Warlock sprite.
You now have an army of skeletons, and one Warlock to rule them all. I will make a warlock, an acolyte/apprentice and an advisor. They are your three nobles, they can learn spells, and so on. I think this will work.
and if your Warlock dies... no worries, just his body died. As long as you have phylacteries and souls and skeletons, you can resurrect him, by simply possessing a new body.
I like that idea, really
but in my opinion only 3 magicians or so are a little bit limited...
so i recently had an idea... as allways, i'm no modder so i'm totally not sure if this is even possible but anyway:
what if you just have different castes wich extremely differing learning rates and some specific starting skills
so every caste would have certain jobs (jobgroups) wich they can hardly change and therefore the sprites would simply fit
per example:
undead corpse caste: natural skill of novice in masonry/mining/stonecrafting -99% learning rate in every other job -> undead sprite
skeleton caste: natural skill in bonecarving and basic fighting abilities -> skeleton sprite
acolyte: some skill no worthless minion could ever accomplish, like praying; -99% on manual work
warlock: sorcery skill etc.
and so on..
For fighting skills especially:
warlocks should be the only ones wich can properly use their magic equipment (magic staves) and those would have a different fighting skill than the crude weapons the undead minions would use - so the recruit/fighter/legendary 'soldiers' would also have different looks.
additionally the mentioned nobles could also be used as different sprites for the most powerfull warlocks.
i know, this
could be bypassed but i think if the player is willing to obey the "rules" it should work.
what is more:
could different castes have a different "biology"?
like if skeletons do not need to eat but also have just an expected lifespawn of just 5 years before they fall apart
undead corpses wich only eat meat but slowly rot
warlocks with certain extraordinary eating behaviors but a nearly unlimited lifespawn