I have found the way to return original portraits for origin characters using savegame editor.
Check this post for savegame extractor and follow instructions there to decompress your save file to xml file. http://larian.com/forums/ubbthreads.php?ubb=showflat&Number=605573
In xml file find all occurences of <node id="PlayerCustomData"> node.
https://imgur.com/a/66Zpl
This node represents some sort of character profile appearence. Inside the node is bunch of "attribute" nodes. OriginName node as name suggests contains name of origin character. New ugly origin portrait is stored in CustomIconImg node. The node has value attribute with long string. This is new encoded portrait image. Delete the string, and leave value attribute empty, like this: value="". Repeat the procedure for all origin characters with messed up portraits.
Now pack your edited save following tutorial above. Load the save and voila! Your origin companions have those great personal portraits again. Only Ifan has portrait that doesn't suit him(see imgur post), I'll use mirror for him once more :)
