I think that {QIpmeH qatlh’a’?} is basically {-meH} used as if it were to be used for a noun, but it’s used on a verb, instead. It’s a kind of verb phrase instead of a verb clause. It’s the same kind of infinitive (or near infinitive, since we are so shy about calling this an infinitive). “Is it difficult to hit?”
The subtext is that if it’s not difficult to hit, I’m not going to bother with it. The whole point of hitting it is the difficulty.
Perhaps a better literal translation would be “Is it in-order-to-hit difficult?”
I had the same thought, but it kind of falls down when we remember the most prominent example of this phenomenon: Heghlu'meH QaQ jajvam. This sentence explicitly mentions its (indefinite) subject, so it is not infinitive.
However, there's no rule I'm aware of that says purpose-marked verbs modifying nouns have to be infinitive. In fact, we know there is no such rule, since we have qaSuchmeH 'eb opportunity for me to visit you.
So whether a purpose-marked verb is infinitive or not is not prescribed in the grammar, which is a big reason why I avoid casually declaring anything to be infinitive in Klingon.
But it's still possible to view purpose clauses as closer-bound to their verbs than other dependent clauses. They are, after all, described as a different class than the other "subordinate" clauses, and they do only appear in front of a verb. It may be that such clauses can be tightly bound to a verb to mean what we're talking about.
However, they're not always this way. Our first purpose clause modifying a verb is jagh luHoHmeH jagh lunejtaH. Notice that the object of nej comes between nej and the purpose clause. This argues against luHoHmeH lunejtaH being some kind of "verb phrase" that gets treated as a verb the way a noun phrase gets treated as a noun. The purpose clause here really is a separate clause.
Maybe the "verb phrase" idea is valid when the main verb is a
verb of quality but not a verb of action. Who knows? This is why I
keep saying we don't really know why qIpmeH Qatlh'a'
and Heghlu'meH QaQ jajvam mean what they mean. The
mechanics of the purpose clause are too unclear for us to be able
to explain them; we just have to take them on faith that they
work.
-- SuStel http://trimboli.name