Feel free to adjust the sweetener levels to your own personal taste. I've found that chocolate recipes taste best with a blend of sweeteners or with granulated sweeteners (i.e. do not just use stevia).
Do not attempt to substitute for the flours unless you know what you're doing. Coconut flour and oat fiber can be finicky and soak up much more liquid than low-carb flours such as almond flour.
For the pudding, be sure to use a gelatin that actually gels (like Knox brand, which can be found at your local grocery store or bulk food store).