I made subtitles with the translations I’ve found around the nets for the LOTR movies: https://github.com/genekellyjr/LOTR-Subs in the Releases section.
I need your aid to finish the subs. Now is the hour, Riders of Rohan - check out the subs and see if there’s errors (I had to use optical character recognition to convert them from the original bluray subtitle pictures) or spurts of Elvish or Black Speech that I missed! Open an issue if you see an issue!
Most pressingly: there are things I was not able to find translated, if you are a wise wizard please lend your aid!
And finally, note I cannot translate and did not translate for this - I merely found the translations (being a simple hobbit and such things)
From my lookin Black Speech and Khuzdul are not fully fleshed out. The GitHub near the bottom in “black speech resources” has links to all the black speech words there are. Sindarin (new elvish) and Quenya (old elvish) are pretty filled out, though. This site is good for words but is pretty verbose https://www.elfdict.com/
There’s a Khuzdul dictionary online but it’s extrapolated words to try and make the language usable, not pulled from direct sources.
Edit: the black speech in the movies is hobbled by the lack of black speech words, they make those few words that have been created work