@Anonymous
you can see the languagesettings for the websites in the website itself:

so, just make sure, that your default languages match in both systems. The supported languages could be a problem as well, but at first the default language can be a problem.
A little bit background: portals generate for every webpage a localized page. So, one page is the root (and determines the route to the page) and the localized version have, well, the localizations. So if you support 3 languages and create a webpage, there should be 4 entries for webpages: one root and 3 localizations.
When the localization does not exist for a specific language, you receive a 404. I do not know what happens with the build-in pages like profile.aspx, when the path to the localization is missing. Never tried to create that situation 🙂
Hope it helps and points in the right direction,
Christian