OK I think we have it figured out! First, I would really like to thank PeteM over at RepGeek for his very informative and thoughtful post. To me, that is what the watch comunity should be about - the watches and trying to help each other with this hobby of ours.
I took two bits of information from Pete -
"And it may be this that is being seen from just a part (as in it may just be unfortunate rather than common place) due to many factors, batching,
contaminants etc"
and
"Using a polish, oil or wax etc is only going to cover and/or polish the area of concern... You need to actually remove it not polish/buff it off... So either a nylon or
cutting compound (not rouge!!) should take it back to that bronze colour..."
I then put his ideas into action. Not being one to go half way, I went all in. I was determined to find out once and for all if I had a plated part, a solid bronze part or something else. Looks like it was a little bit of something else...
I removed the CG and having become pretty good over the years at recreating the brushed finish of a Rolex bracelet with a Scotch Bright pad I went all in. I removed my CG and aggressively re-brushed the finish. The amount and force I used would have easily removed the best plating job. If the CG was solid, I reasoned, the bronze would come through the silver color I was seeing on my CG.
The result was very pleasing. The silver was completely removed and nothing but bronze showed. Using the information Pete provided I have to assume the Bronze Quality Control on this watch is probably not that of Panerai and some contaminants have become mixed in with the bronze alloys. My watch just happened to have some contaminants lurking just below the surface and when I cleaned the CG with ketchup and lemon juice it showed itself. Re-brushing the CG has obviously removed the surface contaminants and lucky for me, the bronze is now showing.
I will still keep an eye on it, but I am pretty confident the silver color on my CG was containments in the bronze alloy on the surface.
Again, I can't thank Pete enough! Here is what it looks like now: