Working CF is pretty straight forward, as long as you keep things clean (I mean surgery standard clean) and pay attention to surface prep (sort of part of my job although I am a long long way from hands on anymore). Sticking in metal, particularly steel, tends to be a bit tricky. Galvanic corrosion issues are in play depending on the resin steel combos. Easiest to avoid it altogether.
Alternatively you could 3D print it!!! I am sure some buddy has a unit sat idle on his desk and is looking for stuff to print… Hmmm I found a lot of cool related bike stuff in the Thingverse but no shimano brake lever so probably not. You would need a CAD monkey to draft it or someone with a 3D scanner too.