This Plug-in for Rhino is relatively new and doesn’t have its own forum. Or at least I couldn’t find one.
On the other hand a short UPDATE on the trans materials for Radiance:
They seem quite difficult to generate also due to the lack of documentation on actual spectrometry data of these materials. Nevertheless, I was fortunate enough to have been shown this widget that helps with trans material generation. Checking the Radiance Manual Vol 2 (1999) is useful for understanding how to set up the parameters.
I have similar issue than yours. I am trying to model a diffuse glazing as realistic as possible but there is not much information about it or cut sheets of this type of glazing with inputs that can be use in Radiance.
I have try to use the link for the app that you share but unfortunately is not available any more. Would it be possible for you to share it with me? did you figure out other possible methods?
For understandin Radiance and trans material generation I consulted this PDF, in which the widget was referenced. DavidMead.pdf (8.5 MB)
And the Widget you can find here: TransWidget.wdgt.zip (371.6 KB)
I used this to generate my trans materials back then. It seamed to work, the renderings looked quite good, but there is unfortunately no way I can say for sure that what I did was precisely accurate.
I haven’t used this in the past 2 years, so I’m not up to date with the current state of the development of trans materials in Radiance. You should definitely get in touch with someone who is using this program on a daily basis or with some developers, they have the best insight on this stuff (check out GitHub)