I'm currently accessing AVS via two devices:
a) A raspberry Pi running AlexaPi
b) an iPhone running Reverb
Both are being used utilizing the same account but while Reverb is working as expected my AlexaPi is telling me, that my account is registered for the US. Bot devices are "answering" in german though.
I tried to fix this by changing the locale of my raspberry, switching back and forth between US and German account via amazon.com/.de to no avail: The AlexaPi still "thinks" it's running with credentials of an account registered for the US.