Do steroids always help heal the skin's natural color within the 2 week treatment, or will it take time for the skin to fully heal depending on how long the rash was there and how deep or bad it was?

steroids attempt to heal the specific rash if if was an inflammatory process. They don't tend to help the natural skin color return. Usually time will help along with some other topical healing products , esp if pigmentation is a concern.

Return of natural pigment/skin tone can take weeks or months after the surface layer is healed. Skin tome reflects pigment created within deeper layers. Timeframe depends on the intensity of the skin disturbance & depth of involvement.