I know (and maybe I even understand it now 
) . I tried to fiddle with that as well and it didn’t help.
With better white balance I was able to hit 80% before some small black dots appeared but by then I am also pushing the data way out of bounds…
EDIT and if you don’t push global brilliance hard like that you can go even to 100 % in the highlights with some of the CB tonal mask tweaks and the artifacts are held in check…