I found that when generating HTML documentation, my examples in my ODD were losing the namespace prefixes from attributes in my namespace. I've poked around, and found that namespace URIs are mapped to prefixes in the template "verbatim-getNamespacePrefix" in the file Stylesheets/common2/verbatim.xsl. I found that if I added an <xsl:when> for my namespace I got the desired results. It doesn't look like there is any parameterization mechanism for me to provide this on the roma commandline.
I'm not sure how to solve the general-case problem (or maybe it's already solved and I don't know about it?), but at the very least, ISO Schematron should be added to the list of hard-coded namespaces.