The Casanii carve symbols into rocks to attract protective spirits.
I imagine different clans of fubarnii would have had different beliefs, but their history has been on of enslavement for such a long time that they probably wouldn't have had much time to move rocks around. Then again, those sorts of acts may have been done as means of petty rebellion, secretly building structures that could be seen by the gods of enar.
So, maybe... Probably not huge structures, but smaller stones, or using stones that are already there. If you wove a tale of a primitive band of fubarnii building more impressive structures, then I wouldn't disapprove