Raising this issue based on comments by myself, @joanmarie, @mcking65, and @matatk from w3c/aria#513.

There, the mapping of ARIA role="region" is conditional on the element having an accessible name. If not, the AAPI role reverts on the native role of the element.

The HTML-AAM unconditionally maps <section> to region, except in the case of UIA. The suggestion in w3c/aria#513 is to map unnamed <section> as if it was a <div>.

Heads up to @richschwer, since you are reviewing the HTML-AAM.