I must be missing something here or Poser and or the material nodes are just wigging out in some conflict.

I downloaded Bantha's Gamma assistant as suggested and used it to convert most of the major components  in the scene. I didn't do all of them, 'cause these are tests, but I did correct the officer's uniforms, the majority of the m4 textures, floor and walls, flags and picture. I did correct the table, but not what is on it. I used the GC button.

I then deleted all lights except the main center light. I deleted the lantern as not to interfere with the test rendering. I did try setting the transparany of the glass to 99.98%, but it was still burning to white.

I set the intensity to 100% and the ISF intensity distance to 30 inches.

However, something is again is creating light under the table and not producing floor shadows. Now my ISF intensity distance might be off to produce shadows now that the scene is brighter, but prior to using the Bantha's python script and changing the gamma setting on most items, that issue was fixed and although a dark  scene without this correction at least it was functioning as I thought it should.