There are a lot of Klingon words that describe various elements of Klingon culture (rituals, foods, planets, etc.) that haven't been transliterated officially but that are, in some sense, "official" Klingon concepts. KGT mentions the planet Morska and rotting forshak. DS9 had "kal'Hyah", the Klingon version of a bachelor party which involves four days of fasting and trials. And so on. If someone took an educated guess at a transliteration for those concepts so they could use them in a sentence, I'd be okay with that. I might get confused if I wasn't well-versed in Klingon culture as depicted on TV, and I wouldn't suggest that mo'rISqa, vorSaq or qalHay'aH end up in boQwI' just yet.

In the case of Huy'reH and cha'ang, the issue is a little different, because the words as presented don't really need to be transliterated. They're already in phonetically-acceptable Klingon. If someone were to ask Marc Okrand for the official Klingon words for those concepts, I feel like his answer would just be "what's wrong with Huy'reH and cha'ang?" (He seems pretty diplomatic when it comes to handling Klingon words invented by others for specific aspects of Klingon culture.) They're not really generic words, they're very specific concepts, so it seems unlikely that they'll be used in a context where anyone involved hasn't heard of them already. If someone sees the word vorSaq, even if they've heard Worf talking about forshak, they might still have difficulty connecting the transliteration to the word they know. But if someone's heard of Huy'reH from the opening of the paq'batlh, they're probably not going to have much issue connecting that idea to the word Huy'reH in a sentence. (It feels a little like asking Marc Okrand what the Klingon spelling for Qov or Quvar is. It's just a name.) My suggestion would be that they're fine to include, with a note along the lines of "This spelling hasn't been vetted by Okrand, but... come on." (Maybe a little more diplomatic than that.)

As for Qich'lut and paq'jachchu, I'd recommend asking first. QIch lut is probably fine to include, I think - if Okrand doesn't vet the paq'batlh spelling (with the ' and lowercase i), QIch lut is probably what he'd go with. It might be useful to have an entry for them anyway, marked with a ? for "dubious canon" and mentioned to have an archaic spelling. It's possible someone reading paq'batlh might not know they weren't "official", and wonder why they're not there.

(I'd also ask if the ' in paq'batlh, paq'raD, et al., is considered by modern Klingons to be the same letter as the qaghwI', or if it's a distinct symbol that just happens to look the same when rendered with DIvI' Hol ngutlhmey QIv.)