Translation:Lurveng is standing behind the building and smoking.
This is an example of a sentence where the continuous aspect (-taH) is misleading and only there because -ing is in the English sentence.
qach 'emDaq Qam lurveng 'ej tlhIch pur
Lurveng stands behind the building and smokes.
If you were saying this to point out that Lurveng is standing there and smoking right now, in English you're forced to use the progressive present tense, but Klingon has no such thing.
Yes, you COULD say that Lurveng standing behind the building and smoking is an ongoing thing, and that would use the continuous aspect, but that's not what someone would really mean when they say this sentence. What they mean is that Lurveng is there and engaged in this particular activity at the moment, not that the activity has been ongoing.
So while qach 'emDaq QamtaH lurveng 'ej tlhIch purtaH is grammatical and does mean Lurveng is standing behind the building and smoking, it doesn't mean that in the sense you think it does. If the English translation had been Lurveng continues to stand behind the building and smoke, it would have been more precise.