Randy, you're maximum vinegar dose is about 4X higher than I was at. I was up to 0.5 ml. per gallon per day, which worked well for me and was afraid to increase it higher. From your results, I would conclude that there should be quite a vinegar dosing range available to hobbyists.
It will be imformative to know how your coral and RBTAs recover from the overdose. Was this a gradual increase in vinegar over time?
The browning could be from a large increase in symbiotic algae. I noticed a browning effect in my RBTA also when I increased my vinegar dose amount. Less expansion, may mean they had plenty of food to utilize without further needs?
Shinking of soft corals, I have no idea what this would mean.