“This fine adjustment is part of the conventional MIDI controller specification, where any of the first 32 controls can be optionally paired with a control offset 32 higher. This is the rare 14-bit Continuous Controller feature of the MIDI specification, and NRPNs simply take advantage of that existing option in the same way to offer 16,384 possible values instead of only 128.” from NRPN - Wikipedia.
Sending and receiving 14-bit MIDI values would be awesome. It is possible to manually build the 14-bit values from the 7-bit MSB and LSB but it would be easier if Vuo could support this out of the box.