Is the upkeep of curly, coiled hair that is neatly and acceptably presented considered a form of dishonoring the hair, which is religiously prohibited, or is it among the permissible customs?

Curling the hair is not forbidden if it does not involve imitating disbelievers. Merely curling the hair does not contradict honoring it. Honoring the hair is recommended, not obligatory, and it involves maintaining it, cleaning it, and beautifying it with oil and combing. The Prophet, peace and blessings be upon him, forbade combing one's hair every day.