Good question. I don't know how much of that was done in this case. I can say that at the outset of the Kix project, they did ask me for advice about pitfalls. (I was skeptical that it could be done at all using the browser technology of that time; they proved me wrong. One of my concerns was proper handling of complex international character sets, both for input and rendering.)

Kix is a drastically different architecture than Writely, so many lessons would not have been applicable. Writely was built on a contentEditable DIV, so the data model was literally whatever junky HTML the browser's contentEditable implementation would create, and synchronization was implemented by performing three-way diffs on the HTML code. It was very much a dancing bear, in the sense of "the amazing thing is not how well it dances, but that it dances at all". ...but I digress. My point is that the mechanisms and challenges of that approach are entirely different than the Kix approach. I think the important lessons would have been product-level rather than code-level.

I dunno, the description you just gave of a dancing bear gives me the impression that your advice must have contained quite a bit of insight about past mistakes to avoid.