If you watered them in the middle of the day and the water stayed on the leaf, the droplets could have acted like a magnifying glass and caused some leaf burn.
One thing about hardening off. Even if the plant was kept outside in the sun, depending on your relative location the sun might be different. At higher elevations, it is cooler even in full sun than at the seashore. If I get my plants from a similar location or from a lower elevation, I can put them in "full sun". But If I get plants I know have been growing in a cooler location than mine, I start them off in partial shade especially during the warmest parts of the year. Even in my own yard, the best time for me to change locations of my orchids under shade cloth to more light is in December when the sun is the weakest. Otherwise just transporting the orchids in the car or moving them out to the sun will cause the leaves to burn. Same with putting orchids in shows. After they have been inside for four days, they have to be retrained to be where they were.
To train plants, sometimes I will put the plant in its pot in the location it is going to be to get used to it before I transplant it to the ground.
Be careful not to over water the peppers. Most people kill their plants with love. When they see a plant in trouble, they keep watering it and end up killing the plant by giving it too much water.
Happy gardening in Hawaii. Gardens are where people grow.