Original language handling
The integration of CATT in the ABAP Workbench makes the original language handling consistent. Test cases have an original language, as do all Workbench objects. When you create a test case, it has your logon language as its original language. All test case texts always exist in their original language. When a test case is copied, the new test case inherits its original language, as it is normally edited in this language.
If the original language of the test case being processed is different from your logon language, you can:
If you want to change the original language, ensure that the texts have already been translated into the new original language. If this is not the case for all texts, you can first copy the non-existent texts into the new language, but then ensure that they are translated as soon as possible.