Yes, you are probably correct assuming a symlink, or at least the pages are identical.
What I did is just search for the words that I know are in the English version, then replaced them. So, to give an exmaple, since I know that there are menu items called “Now playing” and “Search”, I opened the page in gedit and just found these items (ctrl-f). There is not so much text in the page at the end of the day, so that such a “manual” manner of doing this is ok, especially if you have to do it only once. Of course, if you wanted to have several languages supported by several people, (so that every new version is also updated in that language) I guess you could have a scipt that does this automatically from a list given by translators, perhaps? So create a list of menu and other text content displayed to the user in English, posts those on some wiki where anyone can offer translations ideas and people discuss them. Them when the new lists are ready, apply said script.
EDIT: maybe you could even use BeautifulSoup for this…