[TYPO3-templavoila] FCE: How to restrict a translator to certain language?

[Anna Emde]

Hallo,
I have built a multi language Website with Typo3 4.6.18.
Now I would like the translators to be able to edit their own language only (as in the first attempt the translator started to overwrite the content in the default language :-)
That work's fine for the standard content elements: The translator creates the translation for a page, then creates the translation for a content element and then he can edit it.
But as for the flexible content element there is no button for creating a copy. Instead, the fields for the different languages are shown one after the other in the FCE, but you can see (and edit) these fields only if you are allowed to edit the default language.
How do I manage to allow the translator to edit the fields of the FCE which belong to his language?
Regards,
Anna