There is actually a default message on password protected items that is also gettexted and therefore should be translated. Of course only if your server has gettext support and a translation for that language exists. Or am I missunderstanding anything?
Otherwise you also can also call content from a Zenpage on the static password.php page and provide a custom text and manual translation.
Same way as discussed on your older topic actually ;-)
http://forum.zenphoto.org/discussion/1409898/include-page-excerps-in-the-album-page#latest
It's always the same principles ;-)
You need to use the titlelink of the page you want to call the content of. Without the . is a general way of writhing that you should put some fiting string in there as just writing "something" otherwise might mean the value should be "something" itself.
`if the page's titlelink istest`.