And is exposed to the weather without plaster or other facade protection. Therefore, I don't really understand "brickwork later." It will be soaking wet with all its consequences for the interior.
Oh come on. But there is insulation between the stone and the facing brick, right?
Since I don’t see any anchoring for the brick facing, I suspect that it will not be a brick veneer but rather a cavity wall infill. Admittedly, this does not answer the question of tightness – however, in my childhood in southwest Germany, I often saw that new buildings were plastered on the outside only long after moving in.