Learn English – the one word description for someone who likes spicy food

It's a genuine inadequacy in English vocabulary, with no simple fix:

• "Hot" is ambiguous
• "Spicy" is also ambiguous (certain kinds of cake, for example, are spicy but not hot)
• "Piquant" is not frequently used, so could seem pretentious.

You must therefore keep an eye on context, and add information where necessary.

Most of the time, when talking about food, "hot" refers to temperature, except in the context of mustard, horseradish, and non-Northern-European cuisines. So unless you have explicitly established that those foodstuffs are in-scope, it's pretty safe to assume that "hot" refers to temperature.

This is usually called diet, or if you want to be more wordy dietary preferences.