Hi, that's something I was wondering for a long time. In all examples of spoken Klingon I have heard, the stressed syllable in the word *tlhIngan* seems to be the first one: *TLHIngan*. But according to TKD it should actually be the last one, right?
Finally, it should be noted that there are some words which seem to have variable stress patterns, with the stress sometimes heard on one syllable and sometimes on another. This phenomenon is not yet understood. The rules given above do not account for this variability, but if they are followed, stress will wind up on acceptable syllables.
In other words, the rules for stress are a vague approximation, and wherever you see exceptions you mustn't be too surprised. Neither should you expect to be able to explain the exception.
By the way: In the section about numbers in TKD we can read: "Higher numbers are formed by adding special number-forming elements to the basic set of numbers (1--9)". I know, a "number-forming element" is probably not the same as a suffix, but that would explain (at least to me) why these "number-forming elements" are usually not stressed. Maybe is *ngan* not only a noun, but also something like these "special forming elements"?
Number-forming elements certainly are suffixes. They're number suffixes. Numbers aren't nouns, even if they act like them sometimes.
Is ngan a suffix? Maybe. Maybe not. Either way, it
doesn't give us predictive power over stress.
-- SuStel http://trimboli.name