If you have two masses, each moving at 0.9c in opposite direction, the separation speed would be 1.8c. However, your question asked about the speed measured from one of the masses.
I think both clocks will record the same time in all frames. The flash bulb is equidistant between the two clocks, and the clocks are synchronized*, so the reading on both clock faces will show that the light hit them at the same time.
* In the train frame
It helps to draw your diagram approximately to scale. Then you can tell if the answer you came up with is in the ballpark (sanity check). If you draw the correct arrangement of the 1.3kg force vector on the ball, the drag vector you are solving for, and the 25-degree angle in the right place...
1. In this system the sun boils Freon in a solar panel.
2. Freon vapor is sent to a turbine or piston motor.
3. Freon discharge from the motor is sent to condenser coils submerged underwater.
4. The cooled, low-pressure Freon is sent back to the solar panel inlet.
5. The Freon-powered motor...