Hi...I'm not sure If NTA can do that, like what you saw, it can only display the TCP packets and not the number of session. This will be a feature request for the NTA product.
I use the UnDP against the Riverbed Cascades for the current Active/Established/Max etc, obtained from the Thwack Templetes.
This was modified a bit though as we needed to know the amount of Optimised connections depending on the model due to how Riverbed licensing is so we would get notifications is nearing capacity / device license throttling.
can you please post your modified template file
if possible add some comments to indicate what you changed and why
i use Riverbed Cascades, pilot and their wan ACC successfully