The plugin draws a (virtual) line from start point to end point. (you dont need to actual draw that line)
When that line intersects with an 'obstacle', the expressions Trace.HitX & Trace.HitY will hold the exact coordinates of that intersection.
Trace.UID will hold the UID of that obstacle.
So, yes, it detects obstacles only.
Where 'obstacles' is the description that the author of the plugin gave to what you would like to see named as 'targets', i understand.
The plugin (although based on) is not a Line-of-sight detector, it is basically the opposite.