I’m happy to see that you’re making great progress. I’d have to either go back to the Shader Parameters and experiment or refer to the Readme on GitHub in order to answer that question.
This might be one for one who has more intricate knowledge and experience of the bezel customization parameters for e.g. @HyperspaceMadness, @Duimon, @TheNamec or @soqueroeu.
What I can say is that the bezel is sub divided into different sections. There’s the Frame, the Reflective Bezel and the Viewport.
In each section there are parameters which control geometry, lighting and colour and visibility/opacity.
What you’ve circled there could probably be the inner edge of the Frame or the outer edge of the bezel. So you might have to look for a parameter that resembles that, then adjust the Opacity or Brightness.