If you have just upgraded your wiki you are not in the wrong place.
This page describes customizing MoinMoin's language support. New visitors to your wiki can be presented with a front page in their preferred language, or they can be forced to use the page you specify. You can also lock down the language used for translated pages and phrases within your wiki.
First go to SystemPagesSetup and unpack the system and help page packages for any language you want to support.
After that, just read the text below, decide which way you want to go and change your configuration.
For the impatient (you must set page_front_page to get rid of this page being the front page):
# choose this, if most wiki content is in a single language page_front_page = u"MyStartingPage"
# choose this, if wiki content is maintained in multiple languages page_front_page = u"FrontPage"
If you go the single language way, you can copy some of the content of FrontPage to the page you choose as your page_front_page. Alternatively, if you have the rename action turned on in your wiki, you can rename your FrontPage to another name, then assign that name (for example, Welcome) to your 'page_front_page' variable.
If you go the multiple language way, don't forget to edit all translations of FrontPage.
If you go the multiple languages way, people reaching your wiki will be directed to the front page corresponding to their browser language setting. If you did not prepare that page, they will see the default page for their language and have the impression the wiki is empty or badly maintained.