The user can change the desired language using the language button. The project language can be defined once the language options were configured beforehand in Tools (actually only supported under WebOffice flex client).

Change language button and choice in WebOffice 10 R3 flex client
Note: Only released languages (see chapter Options for more details) will be provided by the client.
The user can edit / replace the configured language and its icons buttons in the directory: <WebOffice web application\client_flex\bin-release\com\mysynergis\webofficeflex\assets\images. The image files are named: i_language_<language code>.png. E.g. for projects usint the German language to be released, the user can delete i_language_de.png and rename a copy of i_language_de.png.de to i_language_de.png. The same can be done for the tool icon button: i_language36.png.

Change language button and choice in WebOffice 10 R3 flex client - alternate icons