it reminds of previous project. We had one sitemap component which shows links in html page (sitemap.html) as well as generate XML (sitemap.xml.html)
Each locale had their own sitemap component in its sitemap.html page
and mapping from JCR Resource resolver was used to map these internally.
site.com/sitemap.xml - content/site/jcr:content/sitemap.xml
site.en/sitemap.xml - content/site/en/jcr:content/sitemap.xml
site.us/sitemap.xml - content/site/us/jcr:content/sitemap.xml
hope this helps.
Main idea was to use same sitemap component across different locale but controlled by resolver mapping for execution.