But there's still something I'm wondering. When would it be appropriate for us to put the {-pu'} on a quality verb? Because -if my understanding is correct- I can't think of an occasion when something like this would be needed. So could you write an example where the {-pu'} would be necessary on a quality verb?

I don't think it's a very sensible thing to do, but it might be possible. An analogy would be using the English word know in the present progressive tense. Normally, one wouldn't say I am knowing it, but there might be special circumstances where you would say it. Aha! Now I'm learning it and I'm knowing it! Someone might say something like this to deliberately make the learning and knowing parallel by forcing both into the same tense. You might do something similar with Klingon perfective.

Basically, saying things like jIQuchpu' and SuDalpu' would sound like I happied and You boringed.

Or perhaps does voragh know of a Ca'Non example where we have the {-pu'} on a quality/stative verb?

The only possibility I'm aware of is woQ luSuqmeH jIjpu' chaH romuluSngan'e' je from Skybox S26, but this is a bad data point, because jIj was originally glossed as cooperate and only got the further gloss of be cooperative after this card was published. I don't automatically take every gloss that starts with be as proving a quality verb, so I'm not convinced jIj is one.

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SuStel
http://trimboli.name