While the BSA Supply Division only currently carries Interpreter Strips for American Sign Language (ASL), Arabic, Cantonese, Dutch, French, German, Greek, Hebrew, Italian, Japanese, Mandarin (Simplified), Mandarin (Traditional), Portuguese, Russian, Spanish, and Vietnamese, that does not, in any way, mean that these are the only languages authorized for earning the Interpreter Strip.
You can wear an Interpreter Strip for any language (other than English), as well as American Sign Language, Signing (which is not the same as American Sign Language), and even Morse Code. And no, spoof patches are NEVER authorized.
If you cannot find an Interpreter Strip for the language you know, you can check other sources (i.e., eBay search for "interpreter strip" -spoof), or even have your own patch made... just as long as it conforms to the same standards as BSA-provided Interpreter Strips. It is imperative that you make sure the text of your Interpreter Strip is written in the subject language... not English! (Except, of course: ASL, Morse Code, Signing.)
The Interpreter Strip is not an award, per se -- it's SOLE purpose is to give others an immediate, visual queue that you are able to perform as an interpreter, when needed. That's why the patch is unique in it's appearance; that's why it's placed near your name tag on your uniform; and, that's why it's written in the other language. E.g., Deutsch, instead of German.
Interpreter Strip requirements
Boys and adults may wear this strip if they show their knowledge of a foreign language or the sign language for the hearing impaired by:
*Does not apply for sign language.