Now, if someone wants to pull up a few instances of -nIS
being used where an agency is imposing an action and consequences
of failure on the subject, and not just instances where the
English translation uses must, I'll be happy to revise my
opinion.
I thought of one such example immediately, but I didn't respond because I expected it to have been in the list presented by André. Now that I've had time to read the rest of the thread, I see he didn't include it.
From Conversational Klingon: {vagh rep bImejnIS} "Checkout time is 5 am."
That certainly counts as an imposed requirement, even if a penalty for noncompliance is not explicitly stated.
There's also {lupwI' DalIghnIS} "You must ride the jitney." I think it too is a relevant example, but I can accept someone disagreeing with that assessment..