You went for the "trade off" of correcting a scar with a steroidal injection to the thinning effect and capillary ingrowth from the steroid injection. Thus YES they are permanent...
Spider veins can develop for many reasons including from steroid treatment. Spider veins can be treated with lasers to soften them a bit. Good luck.
In most cases spider veins (telangiectasias) will improve over time after Kenalog or other cortisone type injection.If they don't,you can consider a quick pulsed dye type laser or IPL for improvement.