Tar is used to seal the exterior wall to help prevent moisture intrusion. The men building the foundation should know this, in fact sealing the exterior side of wall should have already been part of the building design.
Sealing interior side will not allow the wall to breath. Before you proceed further I would have an independent Qualified foundation contractor evaluate and see if wall is still salvageable.
The fact they applied tar at interior side shows they don’t have a clue. You need to hire a different building contactor. I’d hate to imagine what else they might do.