Default [Q] Default Translation when compiling own ROM

I tried to build a rom on my PC but every time it exits after warnings like:

aapt: warning: string 'mediaSize_na_legal' has no default translation in frameworks/base/core/res/res; found: az az_AZ et hy ka km lo mn ms ne ne_NP si si_LK

There are lots of these warnings with just different sting-names. I downloadet die Omnirom source, just as it is written in the official thread. I also tried out some other roms like Cyanogenmod and ChameleonOS (both for Tate and m7ul - same warning - same stop) but they all stop compiling after these warnings.
Now my question: How can I add a default translation? Which file(s) do I have to edit?

Thanks for your help.