The Klingon dialogue in Star Trek: The Motion Picture was devised by James Doohan and spoken by Mark Lenard, who, of course, played the Klingon commander in that film. My understanding is that Doohan recorded the dialogue on tape and Lenard then listened to the tape and wrote down what he heard in a way that would help him learn the lines. To the best of my knowledge, Lenard's handwritten transcription of this tape is the only written version of what Doohan made up. (There was more made up than actually ended up in the film. Some of this additional dialogue can be heard -- though without benefit of subtitles -- in a scene where we see the Klingon commander on a viewscreen on a Federation monitoring station. But the Federation folks are talking though all of this, so the Klingon dialogue can't be heard very clearly.) I!! don't know whether at the time Doohan made the recording he or Lenard or anybody else knew which phrases would go with which subtitles or whether subtitles were changed after the filming was done. (Having said that, the command meaning "fire [a torpedo]!" -- which I transcribed as {baH} but which sounds kind of like {maH} -- must have always had that meaning, since it's there a couple of times. [The {H} is pronounced like the final {ch} in the name of the composer Bach.])

My involvement with Klingon began with Star Trek III. In devising the Klingon dialogue for that film, I first listened to the lines spoken in The Motion Picture, copied the subtitles, and transcribed phonetically what Lenard was saying. I also imposed a structure on the lines, deciding, for example, whether the phrase pronounced something like "June tah," subtitled "Evasive," was one word or two. (I decided it was one, made up of two parts: {jun} "take evasive action" and {taH}, a suff! i! x indicating that the action is of a continuing or ongoing nature.) It wasn't until after I had done this and after about half of the lines of Klingon were filmed for Star Trek III that I met Mark Lenard and he told me the story of how the phrases he uttered came into being. (He also showed me his written version).