We're disappointed to hear that you have had so much trouble with the service and hope that we can have this resolved for you soon.
Wi-Fi calling works the same way as VoIP, in that the phone's signal is not actually being extended from your provider, but the call is being made over the internet service. Because the HughesNet service is provided through satellites, there is an inherent delay and this makes services such as Wi-Fi calling a poor experience. HughesNet provides a Voice service, which I see you have, that has been optimized to work more efficiently on the service.
Regarding your actual internet service performance, after running initial diagnostics, I do see that there is something we need to take a look at a little more. I am providing your account information to an engineer who will be investigating. Keep in mind that because of the issues I am seeing, your HughesNet Voice service will also be affected until it is resolved. In the meantime, I am applying a credit to your account while we work on this.