It looks like that one is animated by keyframes. In this case you could make the animation go right to left by reversing the keyframe order and then adjusting as needed. You will need to do this with the Emitter and the Rectangle Mask.
For the Mask:
-Change the Mask Blend Mode to Subtract.
-In the Inspector, go to the X Position and to the right of the keyframe indicator, click the downward facing arrow and select Show in keyframe editor from the contextual menu.
-In the Keyframe editor, option click the checkbox next to the Transform.Position.X channel. this will hide the other keyframes.
-Select both the keyframes for the X channel. While they are both selected right click on top of one of the keyframes and select Reverse Keyframes from the contextual menu. This will reverse the animation direction for the Mask on the text.
For the Emitter:
Basicly, do the same thing as with the Mask. Go to the keyframes for the X postion and reverse them. In this case you will need to adjust the start and end postions. The first keyframe will need to be near the right side of the canvas, and the second keyframe will need to be further away. Once you are close you can adjust the second keyframe to match the mask that wipes the text