Hello,
I am not aware of any guidelines for timber thicknesses and proportion and doubt very much there are any. In fact I would be very dubious if I ever came across such tables as to them having any use whatsoever! There are just simply too many variables involved. Something made to a thickness that looks too thin, might look too thick with just a change of timber used or even a change in the grain selection. Even the style of furniture will have a bearing on how thick or thin the members appear to be or need to be. Then add some edge detail and things change again, so an edge might appear thicker than it actually is with one moulding, but thinner with another. So it is just a judgement thing after structural demands have been taken into account. You need to be the judge, which is where the art comes in.
If it were me, I would slice the wood into 2mm thick veneer and glue it to plywood or something stable. This way, I can choose the thickness I want and not be dictated to by the thickness the wood just happens to be. I can then use the veneer to edge lip and get the lace on the edges too, since the edges of lacewood is pretty dull and the end grain worse.
Mike.
Edit,
Incidentally, I'm glad your wood has not moved after cutting, but quarter sawn timber in general has no garuntee that there will be no cupping. Differential moisture content will make even quartered timber move if you are not careful as the inner surface dries out once freshly cut. I'm sure you have been careful, though.