The damage done to the leaves can be caused by either exposure to cold temps or direct sunlight. You didn't mention cold, so it is safe to assume that the damage was caused by the sun. Dracaena deremensis is a tropical species plant that grows in deep shade in the understory of rain forests. That means they cannot tolerate direct sunlight, but they do very well indoors in relatively low light.
The damaged leaves will not recover and should be removed. With proper care, healthy new foliage will emerge, but only at the tops of each stem, not down below. To eliminate bare lower stems, you would have to prune the stems back to the desired height.
Of bigger concern is the repotting that was done unnecessarily. This plant has a relatively small root system. It should be in a small pot with a good potting mix that drains quickly. That mix would be primarily peat moss or coir with perlite mixed in throughout. If you have access to volcanic cinders, that would be even better. The large pot and heavy compost you used will retain moisture around the roots for long periods of time and deprive the roots of the oxygen they need to avoid root rot. You may want to consider undoing the potting you did and get it back into its original pot. Otherwise, you are going to have to be very careful to allow the soil to dry at least a quarter to a third of the way deep into the pot before adding a small quantity of water.
This plant is a bit more sensitive to fluoride than some other species. However, unless your local tap or well water has a naturally high fluoride content, fluoride damage will not be a poblem. The fluoride added to municipal water supplies is not concentrated enough to be a problem. Fluoride cannot be removed from your water. If you really have a high concentration of fluoride, then use distilled or filtered water for this plant.