Glad to see things are working out. I came to the conversation a bit late.
One thing to keep in mind is that when a tank is still cycling, the fish can become stressed very easily. They are likely already stressed from the move, and there's no telling what conditions they were in at the store. That combined with adding them to a new-ish tank setup that is still becoming stabilized makes for yet another stressing situation.
Fish can often show disease/sickness symptoms when they are stressed, because they are in a weakened state. So before throwing medications at the problem I would first be certain that the water conditions are all good and things are settled, many medications can actually do more harm than good when it comes the tank as a whole.
As far as smartstart goes, my opinion is that it's just another snakeoil product. I tested it once and had no noticeable results, but besides that, it seems like they don't offer much information on what this product is comprised of exactly, or some sort of data or anything. The only thing I found when digging was lots of information on marketing it in stores, relabeling for distribution, etc etc etc.
All said and done, whether a bacteria booster product works or not, don't put any trust in it and just let the water tests guide you.