However, WARNING and NOTE types aren't rendered very well, I *think* - or it's entirely possible that they are rendered according to paragraph type and I just can't tell.

In the AST, WARNING and NOTE generate XML:

<note><simpara /></note> 

When AsciiDoctor generates HTML, it annotates the content with NOTE: and a paragraph with the contents of the note. In Word, generated from DocBook, this annotation (the "NOTE:") is lost. That's sort of understandable, but... how would one replicate the behavior from the HTML backend? The DocBook *has* the types; the AST in Pandoc contains a DIV with a class that maps to NOTE or WARNING, so the context is there, but I have no idea how I'd update the Word output to reflect the NOTE or WARNING type.