Several units used to have alternate models in Reign of Chaos, examples include the Siege Engine (Steam Tank), Demolisher (Catapult), Glaive Thrower (Ballista), Gyrocopter, Priest and Sorceress. These however seem to have been replaced by their TFT versions, even in the Reign of Chaos campaign.
Trying to switch to the Reign of Chaos versions of the models in the World Editor doesn’t seem to be possible either anymore. (Tested with Steam Tank / Siege Engine)
The priest and sorceress are actually there and working as intended. If you play the campaign you’ll notice this. They just don’t change in real time if you tick the box in the editor. But they work in game. I have found the steam tank under a different name. I believe the ballista is in there as a neutral unit, but looks completely different, not night elfy at all.
One asset that IS missing and kinda bugs me is the unused chaos orc ranged model that was hidden in the old editor. I’m pretty sure they reforged some other unused models like the gargoyle spire, but left this little guy out.
I’ve managed to find most of them by checking out the data files with cascview. Most of them just have the word old added onto the regular one, sadly I can’t seem to find the old Gyrocopter model though.
I think they scrapped the flying machine for good.