Alternate Language packs and Authoring and Proofing packs can be added to the Office install on your Connect devices to suit your needs.
Process
Close all Office apps (Outlook, Word etc)
Load Word
Select Options, from the bottom left
Select the Language tab from Options page
Then, you can then safely add any additional languages which are required
As you will see that I have been able to do so.
Although a warning, great care should be taken. Whilst it should only be a simple matter of selecting and adding the Language that you want to add.
You MUST ensure that you untick the options at the bottom which will make the added language the default display language before hitting Install.
As otherwise things don't work out so well, as the alternate language would be set as the default as below.
You can also add any additional language Authoring and Proofing packs using a similar method with the second part of the window if they are required.
Although unlike with the addition of language packs, this time you select the language and you should tick the option Get Proofing Tools if it shows as being unticked after you have selected your required language, so that the Proofing tools are downloaded, before you hit the Add button:
These changes will often prompt for all Office apps to be closed while they complete the update process, but the process will prompt you accordingly as required.
The update can take a few minutes to run in the background.