Don't bother with waterproof labels, too costly.
If your are retailing honey or a volume then:
Make a warming container with an old freezer (good insulation) and an oil column heater that has a thermostat. Set the heater to run at 38-40C. Get a good thermometer, any error will ruin the honey if it gets too hot.
Place your candied honey in and wait, 24-48 hrs and your have your honey back.