Microfacet Roughness Workaround?

[Olyandros]

Hi,
I ran some render tests in LuxCore for nested dielectrics and noticed that the rough ice cubes in the scene get really dark. As far as I looked into it this is because of improper energy conservation due the lack of microfacet roughness calculation. Now my question is if there is a known workaround for this kind of material?

Here is the blend file:
https://nx45603.your-storageshare.de/s/f3qZJRr2BQPYYnk

[kintuX]

Disable roughness and make it micro bumpy
Also note that LuxCore reaches max. roughness at 0'8.