Rendering Admonitions and Callouts in Docx

I'm a tech writer for a software company that uses asciidoctor for the entire product portfolio's offline documentation. Our adoc files are typically exported to and delivered in pdf/html format, but for a specific sub-set of projects, some documents will have to be delivered in docx format.

So I've cobbled together a method of converting adoc files to docx format, via docbook + pandoc + some nifty macros to adjust tables, numbering, images, etc. It's looking real good, but two details remain problematic:

1. Rendering callouts in docx.
2. Rendering adoc admonitions in docx.

I've been scurrying the interwebs for different approaches, but apparently there are none to be found.

I figured it would make a good discussion here.

Any ideas?