Copernicus has limited multilingual support. You can change the language of the user interface from the Language menu (figure 1).
fig. 1
Be aware that not everything in the user interface will be translated. The author needs translation help from anyone who is bilingual and would like to see better support for Copernicus in their native language. Please contact the author at will@tanksoftware.com, he will greatly appreciate your help.
Technically, the language table is loaded from the file "data/language.tdt" in your installation directory. That file is a tab delimited text file UTF-8 encoded. The first column contains the English passages, and in the remaining columns the French, German and Spanish etc translations respectively. It is possible to edit that files, if the translations are incorrect or absent. I reccommend using jedit (http://jedit.org) if you are, making sure that you set it to UTF-8!. If your language isn't listed, you can use the "Custom" one. Other languages can also be added to the main distribution of the program, please send the author (email above) your language.tdt files if you would like to see a new language listed.