There are also SilhouetteBias and SilhouetteScale parameters to adjust the inner lines, but they don’t seem consistent in this sense on different zooms. Not sure if it helps, but you could try if some values like x10 or x100 from default 5 would make difference. I didn’t find any good explanation Castle Game Engine: CastleRenderOptions: Class TCastleRenderOptions
You could also try and see how it work on an example project in my topic [ISSUE] 3D complex models hittest