Hehe, Klingon subtitles would be the ultimate.
It’s hard because the Klingon script is more-or-less exclusive to the Klingon language, so you’ve still got to do the heavy lifting of the translation. And asking for the Klingon word for lightsaber could be asking for a fight.
Tengwar, on the other hand, could easily just transliterate English subtitles. Yes, I’ve thought about this way too much.