[TYPO3-mvc] extbase - backend and multilanguage with n:1 relation

[Domi]

Hi,

I have a question to the language handling in backend with translated 
content of related content.

My setup:

2 languages, english and german

I have "travel" and one categorization field "traveltype" as a n:1 
relation inside of my model.

After creating and translating all "traveltype" fields inside of the 
backend I add one travel.

In the dropdown traveltypes of all languages getting displayed.

How can I set up the TCA to show only records related to the choosen 
language? Or any other best way to handle this? Currently its configured 
as a type=>select.

Thanks!

Dominic