Merlin is delivered in 3 localizations: English, German and French and is compatible with the Mac OS X system preferences. This means, is your Finder running in French it will also run in French. Is your Finder running in Dutch and German is listed after it but before English, it will run in German.
To change the preferred system language in French for example, just call the ‘System Preferences’ and the ‘Language & Text’ pane.
Switch to the ‘Language’ tab. Select the language you want to have as your standard language, drag&drop it before the top most entry.
If you now start Merlin, you will see it run in French. Your Finder is by the way not yet French, but it will be the next time you restart it.
We sometimes get asked, how to define the language of Merlin in English when having a French system.