I've got virtually none of the cosmetic dlc (and don't have all of the gameplay DLCs) so I don't actually know what any of the stuff looks like. I'll mention it to Vierwood and see if he can get the cultures to use better unit packs as he has all/most of the DLC afaik.
As for custom unit graphics, will probably look into it down the line (if the game supports a format I can work with through Blender) but not a priority at the moment.
I've got everything.
Basically the Riverlands, Westerlands are using the odd Pagan; http://www.ckiiwiki.com/File:Fino-Ugric_unit_pack.jpg
Which looks really odd given their geography.
If you guys just went through this list and assigned the graphics appropriate to each location better.. thatd be great.
http://www.ckiiwiki.com/Graphical_DLC