Don't forget that Vader's eyes also are noticeably red as he stands on the bridge of the Devastator near the end. Not quite as much as the Krennic scene, but still notably so. I don't know how visible it would be in a camrip but I remember it from the theatre. Due to this I'd enjoy it if the red lenses were a little more visible on the Hot Toys release.
They still appear black in the majority of pictures, though his lenses only appeared completely black while in dark environments in the movie.
Let us know if you find a good solution. I'm surprised the reflective material doesn't work out so well.
Yeah that scene was the S####