Loss of communication triggers a RTH. Basically a failsafe setting for loss of signal.
Loss of power will certainly stop communication, but that loss is not the cause of a crash. When you lose power the spinny things stop turning and you crash. But they do not stop spinning because you lost communication.
Flight controllers (the brains inside the aircraft) sometimes fail and cause a true flyaway. Sadly more than a few "flyaways" are simply loss of orientation on the part of the pilot who then flies into something. Neither of those are caused by a loss of communication.
About the only concern related to the antennas is they they are connected correctly. They are pretty foolproof. The strongest signal on the 2 longer ones is perpendicular to the long axis. Don't point them directly at the aircraft.
The mushroom in the middle is the camera control and video feed. If you replace that with the flat one included by Yuneec you do want to point that directly at the aircraft.
Make sense?