I also took one photo in real high ISO 16,000 and the results were so so.
Now for some bad news: The inner RAW viewer on the A99ii probably creates a jpeg version of the photo taken that does not represent the final output really well. I wasn't really sure that the photo about of the bride in tears was in focus until I get home and offloaded the photos. Even zooming all in, I wasn't really sure. I guess I could have used Wifi to take a better look, perhaps I will try it next time. I am pretty sure now that I can't rely on the internal viewer, even when zoomed in, to tell me how good the photo would look later on. I do hope Sony will fix that, but I am not holding my breath as the previous A99 model didn't receive any update except for accommodating some lenses.