The plugin automatically remaps the coordinate system from Leap space to UE space.
That said, if you use the convenience hands you can modify the coordinate by just parenting a scene node; if you use blueprint custom or C++ you can modify the output you receive from the plugin by multiplying the output by a transform. Optionally you can modify this file: https://.com//leap-ue4/blob/master/Plugins/LeapMotion/Source/LeapMotion/Private/LeapInterfaceUtility.cpp to change the coordinate system transform globally for all output from the plugin.