Sitemap plus is actually a plugin, not a stack. As far as I know stacks (the plugin) works fine without Rosetta.
A agree it’s a shame that sitemap plus hasn’t been done in the universal build.
In March of 2021 (15 months ago) the status for the Universal build was listed as “ soon “.
Not sure what the timeline for this is now that YourHead is building a RapidWeaver competitive product.