So this is an interesting one. The current URL doesn't include a locale prefix, so that shouldn't be required. As it is /about/manifesto/ will 404 because that URL doesn't exist. We have to add the passthrough for /en-US/about/manifesto/ for /b/. Since /about/manifesto/ doesn't exist so far though, we can go ahead and do all locales, and add redirects from the old localized pages as they're done. So I think it should be:

```apache
RewriteRule ^/about/manifesto\.en\.html$ /en-US/about/manifesto/ [L,R=301]
RewriteRule ^/(\w{2,3}(?:-\w{2}(?:-mac)?)?/)?about/manifesto(/?)$ /b/$1about/manifesto$2 [PT]
```