You shouldn’t damage the Crumble by powering a Sparkle from an output. Each output has a series resistor to limit the current in the event of a short (it also means a standard LEDs can be connected directly). When the Sparkle is set to white at max brightness, it will draw about 50mA. If it’s powered from an output, then it will only be able to pull about 15mA. This will effect the brightness and colour (white appears slightly yellow-pink, because blue is affected more).
Hope this is helpful.