Question: Air Brake System - Relay valve, and Spring brake valve (Balanced position)

You are correct, yes
It should put the relay valve into a balanced position as long as there is no air leaks in the system. If there was a slight leak at the one brake pot it would come off balance.
Relay valve manual attached, you may have read this already. Might be a help to someone else.

 

With the unhelpful posts cluttering up this place I'm not so sure

 

Any posts that takes a side swipe is particularly unhelpful and would be the last one on the list on my end. As far as trolls and other issues with any site, tribal virology so to speak among the Community will take care of that fast enough if it is outrageous.