Well done with your analysis so far. While it's true that the 1C switch is open when the 4C switch kicks the ball, the 4C switch is at the very end of the 120 degree Score Motor cycle (refer to the Sequence Chart on the schematic). Very soon after 4C the motor will reach its index position and the 1C switch will close. (The 2B switch in the P relay path will open and close in that time too.)
The Trough switch is on the far side of the trough from the out hole - over the hump in the middle and just before the shooter lane. While the timing may seem tight I think that the time it takes the ball to reach the Trough switch is much longer than the time it takes 1C to close.
/Mark