Overriding the materials of a visual model with Meshcat

[Cadeyrnnn]

Hi,
I just started using pinocchio and came across the idea of displaying a copy of a robot at its target configuration. I want the copy to be transparent for clarity and I found an example that is supposed to do exactly that using the Meshcat visualizer (at least that's what I think).

However, the example seems to be broken as the two robots displayed have the same color (even when I replace the deprecated color argument of the loadViewerModel() function by the not deprecated visual_color). I tried it with other models and it seems to work with models created from URDFs in which only the color is specified. The problem is that I am using this arm which has more complex materials and isn't affected by the visual_color argument.

Is it possible to work my way around that? For instance by looping over the different geometryObjects of the visual model and modifying some property ?
note : it is imperative that Ii use the Meshcat vizualizer.

[Cadeyrnnn]

I tried looping over the geometryObjects and setting overrideMaterial to True but it didn't have any effect.