The FD3S chassis was always intended to be a very driver centric experience. This focus on the driver made it so plenty of the components are not interchangeable when the driver moves from the right side to the left side. While some can be easy to spot, others, like the wiper arm assembly are a bit harder to see off hand if they're intended for a RHD or LHD car.
When you compare the driver's wiper arm mount, you will notice that they are mirrored to each other.
Interestingly however, the passenger side remains identical on both versions. the length of the arms also remains unchanged when the driving position changes sides. This is because although the wiper motor changes locations with driving position, the passenger mount is still used as the pivot arm between the motor and driver. The driver position mount is the easiest way to spot differences.
When you have your wiper arms in the orientation illustrated above, turn the driver mount all the way counter-clockwise until it reaches the stopper. The right hand wiper arms will have two of the mounting bolts facing the wiper arm and one facing away. The left hand assembly has only one facing the wiper arm while two face away.