As a producer and daily user of CS, using my own generators, I get the same tarnishing of the silver rods. All I do is monitor the production periodically and remove the generator occasionally, wipe the rods clean with a paper towel and then re-immerse again. I don't want a current limiter on mine as when I need a quick high ppm batch for an emergency or such I simply use rain water and get a much higher ppm result. In my daily maintenance program I use ONLY distilled water and add NOTHING to it.
Low Voltage CS generators, as used in the home, produce a higher ionic content than particulate content. As JAB said, the color change signifies ions agglomerating, or sticking together if you like, which is the classic sign of particle content when shining a torch beam or such throught the solution. You won't see the torch beam through a solution which is mostly ionic in content. You may also notice that it may go from clear to color appearing after 24-48 hours or so. Again this is as the solution stabilises over time and some of the ions form into particles.
To me, clear is fine...I know there are ions and particles of silver present but mostly ions, as a meter will show.
Yellow is fine...I know there are ions PLUS particles but particle content is a little higher.
Any other color I am not familiar with as I don't allow my CS production to go any further.