No that's not the source of the problem, that refers to the Effects directory in the flightgear data directory.
From what I can see the effect behaves a bit strange, the "simple" solution would be to use two different effects, one for the painted objects, and one for the chrome objects, but that just defeats most of it's purpose
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As a starter, this is a quick test of a more "developed" greymap:
I would expect the lighter surfaces to be more reflective than the darker ones, but the difference is very, very tiny here
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Also you can tweak the <refl-correction> in the effect file, it takes values between -1 and 1, with negative values reducing reflection.
Now I've noticed that you've assigned <reflect_map> to a 0.1 value. That's not quite right, as it is a "boolean' value, taking only 0 or 1 as values.
Gonna do another quick test and will report back with my findings.