Maybe you're trying to do something fancier than what I'm understanding, but I think you're making this way harder than it has to be.
The GRIP pipeline code can go right into your robot program and there is no need to use Network Tables to communicate the results - other than for debugging possibly. If you haven't already seen this screensteps document, it shows how to intergrate the GRIP pipeline into your program.
Using Generated Code in a Robot Program