I've leveled all my crafting classes to at least level 10 except goldsmith and cooking. Ever since they tweaked rapid synthe, I've been using Standard and Bold all the way and I've seen sparks coming out from my synthe sometimes but they never turned chaotic on me until yesterday.
I was doing my Armorer leves at the level 1 camp, it was raining and I was just crafting under the rain. My Armorer was level 9 and I was doing a level 1 leve. When Maker's Muse kicked in, I was using Standard synthe, then without any sparks, the crystal ball turned chaotic on my third Standard synthe. It didn't only happen once, but it happened twice on the same leve! I was using Standard synthe a couple of times in a row and without any sparks, it just turned chaotic. So it makes me think if the rain would make any influences on synthing.