Well there are numerous places that either seem to twist from one set of normals to another, or actually have entire polygons with reversed normals.

This causes havoc with how the shader interprets interactions with light. By me putting a proper wood shader here, it becomes clear that the geometry is totally messed up.

I marked up some of the issues I saw on just one section (fireplace).

The wood panels on the right here are behaving correctly. Those on the left are not.

And the fireplace has issues, too.

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Renderosity forum reply notifications are wonky. If I read a follow-up in a thread, but I don't myself reply, then notifications no longer happen AT ALL on that thread. So if I seem to be ignoring a question, that's why. (Updated September 23, 2019)