Personally all my experience is with butter various nut oils , olive oil and tinctures. That said I have found that roughly 190 degrees sees the least degradation of the cannabinoids. One process that may be of use is to actually make an alcohol tincture and then evaporate out he alcohol with low heat creating an extract. The extract can then be added in measured doses to warm cocoa butter, though it likely will need to be warmed first to aid in it mixing uniformly throughout the butter. Naturally the strength is going to vary by plant strain, and harvest so each batch has to be individually tested, but once evaporated it is easy to test for potency and determine the appropriate quantity of extract per batch of chocolate.
One thing to note is that using a super tincturing method is best. That is where you grind the plant matter and then add the alcohol until the plant is submerged by a good inch (typically 750ml of 195 proof alcohol to 1 ounce of mmj) blend well and place in a 3qt pot. place on ELECTRIC heating coil and slowly bring to med. low heat wherein you start to get pin bubbles forming. Lower the heat to maintain just a pin bubble and stir occasionally. Heat thusly for 12 minutes ( sometimes the plant may urge you to stop at 10 minutes or continue to 15 minutes - that's between you and the plant) remove from the heat and poor off into a jar. After it cools, strain and squeeze the last of the alcohol out of the plant matter. Notice you now have an emerald green tincture. Now you can use the tincture for in liquid filled bon bons and such or add to chocolate recipes wherein the low heat levels will naturally evaporate off the rest of the alcohol.
It is interesting to know that if you use 90-100 proof alcohol and the same process, you can actually kill the THC while keeping the rest of the cannabinoids such as CBD. This tincture comes out very tanic looking - brownish, rather than green. If you use dense couch lock type strains such as NYC Diesel or Bubblegum, or other heavy Indicas, you will get a powerful aid for insomnia, relaxing of smooth muscle cramps, aid for indigestion, stomach upset and wasting syndrome. It will also aid in the relief of menstrual cramping and other symptoms as well as for the easing of tension headaches - all with out the psychoactive high. I have not tried it myself but I would guess it might give aid in the other health issues in which CBD has proven to be effective medicine. Since this tincture has a higher water content it is going to be a bit more tricky to use in chocolate recipes, though you could likely pre-evaporate, and thus concentrate the tincture moving it toward an extract.