it would be cool if it was possible for Eventide to be able to both recieve midi and messages from the USB H9 control at the same time
Sorry – not possible. There is essentially only one port, which can be used for either MIDI or USB. When the product family was designed we had expected the USB only to be used for updating, and had not anticipated it being used for real-time control.
maybe a tab in the H9 control app could somehow allow for a choice between midi or USB
Better news here – H9Control can work over MIDI. Leave the USB unconnected, then hit the "Manually Select a Device" button.