Seems that certainly arrow carts can gain the vampiric aura buff which allows them to heal.
We noticed this last night when trying to take hills in Drakkar Lake border land. A superior AC we could just about hit with meteors took about 10% damage from each meteor but after several minutes we were wondering why it hadn’t died. Then we noticed it had vampiric aura buff and was healing itself.
I would assume this also works on other siege too but will check when I get in game.
Note: Not accusing Drakkar Lake of knowingly using this, just saying how and why I noticed.
Edit: Screenshot attached showing cannon with vampiric aura buff.
