Thanks everyone for the kind comments!
I note that you have gone for a princess-seam construction on the back of the coat - although you did not end up getting the reinforcement triangles, perhaps you could sew two matching buttons on (referencing frock coats). I think it would be a good replacement detail (and faster/cheaper than sending it back).
That's a great idea, I might try that. However I'm afraid it could be too formal for regular CBD.