Though anecdotal, thank you for this. I'll go further to say that my own anecdotal observations, both in captivity and in the wild, are similar to your own. I'd say that the ideal PH range is 8.05 - 8.15 and we're definitely pushing the lower end of that range right now.
https://www.epa.gov/climate-in...
But, I'll add another observation the cause of which I cannot explain with certainty. While I see bleaching, die offs, and failures to grow on many reefs attributed to temperature and acidity, I also see some reefs in the same temperature and acidity that are absolutely pristine.
I've even seen pristine reefs in waters with a PH as low as 7.95. The only difference between these reefs that immediately jumps out at me is that the pristine reefs are isolated. The pristine reefs are far away from human development and its runoff. But reefs closer to human development suffer bleaching, die-offs, and smothering algae growth, even with higher PH. In some cases pristine reefs were at the upstream(current) end of islands where all other more downstream reefs were severely degraded or completely dead.