Generally speaking, you should look up a plants point of light saturation (the level at which more light will no longer increase photosynthesis) and the temperature at which a plant changes from photosynthesis to photorespiration. The trick is to find a happy medium between what the plant wants ideally, and the climate. I’d imagine a coffee plant would have a low point of light saturation, and the shade would mitigate any heat stress, for a net win. Any plant that has a higher point of light saturation would be hurt by too much shade. Some golden kiwi growers in our area (central California) put up huge shade houses with black shade cloth to “protect” their vines, and give them a cooler climate (which they did) but the lack of light lead to small, low solids fruit, because the light level was so low. Generally, a white shade will diffuse the light but also reflect some up, so it might be a better fit in a case like this example.