Interesting question, but for practical purposes, I think it is a dead end.
If you want something resembling a Lindt chocolate bar, you cannot make it at home. You just don't have the machinery needed to create the needed particle size of the starchy phase. There is by the way no "cocoa mass containing no cocoa butter or trace amounts of it", the best you can get is strongly defattted cocoa powder at about 5% cocoa butter, and that is already so dry that you couldn't have it behave as "cocoa mass", you can only get is as powder. And this powder particle's sizes are several orders of magnitude larger than those needed for a chocolate bar. You need a tightly controlled industrial process with specialized machines to make the bar from that point. Even if there are manufacturers who have managed to engineer a similar process with shea butter as a substitute, you can't replicate it in your kitchen.
If you want something else instead of a smooth bar, the best you can get will be some liquidish product, maybe a ganache or a hot chocolate replacement. There you don't need tempering, because you dissolve the whole thing and emulsify the fat, it is no longer sitting around in crystalized form.