It'll take a while, but they look like they're recovering. I've had two major bleaching incidents. Depends on a lot of factors but I put it at 2-6 mos to get full color back - just my experience. Stability is the key - parameter swings, drastic changes in lighting intensity, etc make my nems pretty grouchy. Had a couple that were completely transparent and they came back. Just left them alone and hooked 'em up with some bonus target feeding (I don't feed my BTAs but maybe once a quarter, or maybe for company that want to see the om nomin' action).
If your bulbs are older than a year it may be time to replace 'em - just a minor suggestion/consideration.