First, be sure it is paint and not some kind of plating. Try rubbing the dull areas with a soft cotton cloth and some toothpaste. Different brands of toothpaste contain different amounts of fine abrasives, which is what you want. If toothpaste helps, a coat of automotive car polish (wax), will bring up a little more shine.
For more severe damage, you could try using more aggressive products sold for automotive finishes. Rubbing compound is moderately abrasive - so don't go crazy. Rubbing compound works by removing the top layer of oxidized paint, so if the paint is very thin, there is some risk of removing too much, especially on the corners and edges. Polishing compound is similar, but has finer abrasives - so it is safer (and slower) than rubbing compound. Use a quality automotive wax for the final shine.
Might be good to test the process on a less conspicuous area like the bottom of the camera, if possible. The process will be somewhat messy, so I would try to mask any surfaces that are adjacent to the painted surfaces you will be working on.
To be clear, I have never tried these products specifically on a Rolleiflex. But if the finish is some kind of lacquer or enamel paint, it should be restorable using products made for automotive paint. These products are often used with machine powered polishing tools on cars, but I would suggest hand rubbing, only, on your camera.