Currently no release dates or estimates for localised versions are available. Sibelius clearly states that the application WILL be localised. As soon as more information is available, it will be posted here.

Sibelius is localised into a lot of languages, including the manual. If you own any non-English version you naturally have to adapt all things described in this wiki to your language.
Please note that the English version of Sibelius is always the newest one - it may take a while for localised versions to be released.
This page describes a few things worth knowing when dealing with these versions.

The Sibelius website adjusts its content according to the country preference you set when first visiting it. Different countries have different options on the site. By clicking on “Support” on the upper right you will get to the incredibly useful Sibelius Helpcenter. Do not just confuse this section with general support!! You will find discussion forums there, video tutorials and tons of plugisn to download! There is a link to it in the help menu of the application itself, just in case you forget the url.
By the way: Not all products Sibelius makes are available in all countries. For example the U.S. page does not feature the stripped down Sibelius Version called “Sibelius First” (which is because it is not sold there). So if your English is reasonably good (i.e. if you understand this text), you may consider switching to the UK Site, because this one is the “best” (Sibelius Inc. is based in the UK) and has lots of information including nice articles on recent uses of Sibelius in the music business..

If you feel the burning desire to update your copy of Sibelius to the most recent version, you should do this by using the “Check for Updates” option in the help menu. Sibelius will then open your standard browser to check if there is a new version available and will provide you with the correct update matching both your current version as well as your language. If you try to install an English update on top of a localised version, you will end up with a complete language mess. In contrast to the official statements from Sibelius the application will still work, because the updates are technically compatible, but you won't have much fun with it.
You should however never, ever update right in the middle of a project!

You probably know this, but: Sibelius is distributed by several distributors in different countries. So for support issues, please contact this distributor. This most of all applies to upgrades from one major version to another. Though it is technically possible to submit bug reports or feature requests through the distributor (especially when you are writing in any other language than English), it is the quickest way to report those things directly to Sibelius.