Confusing mixing of tenses 2

Question

I have more confusing sentences that were written by native Americans that seem to mix tenses. I'm not sure why these can be correct.

We noticed that you have created a return label for this order.

Does this make sense? Isn't it wrong like the sentence that was determined wrong in my previous post ("She has agreed to my terms, so I only did my part yesterday")?

You don't want to do this. Trust me, I wish I hadn't.

Why not use "I wish I didn't"?

We enjoyed peace. If only it had lasted.

Why not use "if only it lasted" when this hopeful sentence took place after the peace they enjoyed was gone?

"It has been a long time since all of us have been gathered in one place."

Why not "since all of us gathered in one place"? Don't people usually say "Ever since I read that, I've become smarter" instead of saying "Ever since I have read that I have become smarter"?

"I had been told that anyone who did that becomes a bad person."

Why should I use "had been told" when somebody doing something bad isn't relevant to what I've been told?

"People who have had their belongings taken will turn into miserable people."

Why not say "people who have their belongings taken will turn into miserable people"?

Answer 1

1. We noticed that you have created a label ... The writers saw the label at some point in the past; consequently they employ the past tense (they might equally use the present perfect) The sentence is about the label; presumably it still exists and they are writing to say what they will do with it or to ask what they should do with it; accordingly they employ the present perfect, which signifies the present state brought about by a past event.

2. You don't want to do this. Trust me, I wish I hadn't ... The speaker is citing evidence for the assertion that you don't want to do this: "I did it at some point in the past and now I wish I had not done it." The past perfect form is employed to signify a hypothetical or unreal past action.

3. We enjoyed peace. If only it had lasted ... Again, the past perfect form is employed to signify a hypothetical or unreal past action.

4. It has been a long time since all of us have been gathered in one place ... In this case you are right: the best way of expressing this would be were gathered. This is an instance of colloquial imprecision which probably none of the speaker's audience would notice.

5. People who have had their belongings taken will turn into miserable people ... This one is very complicated. The second HAVE here (had) is used in a fairly uncommon sense: it is neither a perfect auxiliary nor a causative auxiliary (to have something done) but the lexical verb used to mean “experience” or “suffer” and taking as its direct object a non-finite clause with, very unusually, a bare infinitive as its head. Thus:

   She had her house burn down = She experienced her house burning down.

   Moreover—as if that were not complicated enough!—when the complementary clause is cast in the passive voice, the infinitive BE is dropped, leaving only the passive participle:

   She had her house struck by lightning = She experienced her house being struck by lightning.

   What this was all necessary for was to establish that in your alternative version, have their belongings taken, the main verb in the relative clause, have, would be in simple present form. But the simple present expresses action which occurs regularly or repeatedly:

   People who smoke = People who smoke habitually, every day, all the time

   When your author writes of people who have had their belongings taken he does not mean people whose belongings are taken habitually, every day, all the time. He employs the present perfect because he is speaking of the trauma suffered by people who have been robbed just once.