Yes, it will curdle if cooked on a high heat or if it is too thick. Never place a block of creamed coconut directly onto a heated surface as it will burn. Always melt it down with enough water to cover, either on the stove or in a microwave oven.
When a recipe calls for coconut milk to be added at the end, it is to prevent it rendering down to oil during prolonged boiling. If a dish does not require more than 30 minutes of simmering, it doesn't matter when you add the milk. But once you have added it, do not stir the dish again until ready to serve.
** Asian Recipes