This is cool in theory, but kind of annoying if you are trying to modify the roll with something like Favored by the Gods from Divine Soul Sorcerer that specifically can activate if you fail the roll.

You add an additional 2d4 to your attack/save that fails.

I’m not sure if ANY other dice modifications work after knowing failure, but I know this one does. I know when I play divine souls I always like to save it for those random Int/Wis saves that’ll get ya.