I have never actually tested metronidazole or acriflavine out on uronema, so I cannot speak first hand of their effectiveness. However, the literature mentions both as effective treatments.
My MO for treating uronema is administering a FW dip or formalin bath, followed by CP treatment in a QT. I know that works.
As callous as this sounds, I would ditch the chromis. Treat them if you like, but never put them in your DT. It is not worth the risk IMO.
As for your other fish in QT, I would dose metro every 48 hrs for at least a week. Transfer the fish into the DT a few hours after administering the final dose in a week. Odds are metro won't completely eradicate uronema from a tank, but rather prevents the fish from being infected.