Completing the wing does not give any major clues to the flap operation, we're all still waiting for details. Best we can do is an educated guess. We know that they are cable operated, there is a pulley bracket on the aft spar, and that a pushrod comes through the spar to attach to the flap.
I think the cables run to a pair of pulleys, where they separate and the upper cable goes through the aft spar to a bell crank that is mounted to the inboard mixer box. The other cable passes through the cove rib and connects to the other end of said bell crank. Pushrod carries the motion from the bell crank to the flap.
The holes are there. Notice the slightly offset hole near the pulley bracket for one of the cables. Also the holes in the cove rib and rear spar. There is good access to the mixer box area through the lower skin.