Steps to reproduce:
1. Go to Control Panel > Portal Settings > Display Settings and select English (US), French and German as current languages, save.
2. Go to Site Administration > Configuration > Site Settings > Display settings and make sure that "Use the default language options." is selected.
3. Go to a page and add a Calendar and a Language portlet.
4. Refresh the page.
5. Change the language to French.
6. Add an event, fill out the title and description (French flag is marked), save.
7. Look for the event in the Calendar portlet, the description is there.
8. Now change the language to English.
9. Edit the event (still in English).
10. In description, change the language to French.
The description shows.
The description doesn't show.