Once the soil drys, I would separate the cluster plants into individual plants.
If they were mine I would throw away the ones with sunburn.
They will eventually turn dark where burnt and will always have the scar.
As they grow bigger the scar will inhibit growth on that side.
The decision to toss plants is a very hard one for new growers.
Eventually it comes down to the question:
Am I running a hospital or do I just want to grow healthy, happy plants?