Test zip with meshes and (an actually working fixed this time) level: http://yorkshirerifles.com/downloads/toneMapTest.zip
ToneMapping is not behaving nicely with devhead (downloaded from github 3rd August 2018)
This seems mostly to do with "representedInLightmap" going belly up on non-lightmapped materials.
With theLevelInfo advancedLightMapSupport OFF, sun representedInLightmap ON = everything dark, tonemapped and non-tonemapped geometry, and emmissive is blurry.
With theLevelInfo advancedLightMapSupport ON, sun representedInLightmap ON = tonemapping good but all non-tonemapped geometry dark (getting no light at all), and emmissive is blurry.
advancedLightMapSupport ON, sun representedInLightmap OFF = everything gets light, emmissive is fine, tonemapping is visible but isn't fully lightmapped due to sun's light. This is all expected.