Is there documentation on how much you have to modify the normal factor? A quick test with division by 10 or 5 (5 -> 0.5, 0.5 -> 0.1) was satisfactory, but is there a “right” way to correct old textures?
I don’t believe your interpretation is correct. There are four textures in the slots, the demo pic was rendered without the second texture, and obviously the lighting was changed a bit.