This question is about my understanding of the nuances about sequence of tenses and conditionals. I provide some examples and my interpretations down below.
If my interpretations are incorrect or the tenses used in the examples are wrong, please tell me. I also believe many learners can benefit a lot from your answer.
When the clause is about something hypothetical, I think we use the subjunctive form in the noun clause.
(1) If aliens came to earth, I would imagine that the human race were going to be under great danger.
My interpretation: The coming of aliens are hypothetical, so the were is a usage about an imaginary situation aka the subjunctive.
(2) If she were elected president, I would suppose that the country were being on the right track.
My interpretation: It is hypothetical that she were elected president, so the were is a usage about an imaginary situation aka the subjunctive.
When the clause is used to mean something real, I think we use the tense accordingly depending on the context.
(1) If she were me, she would understand what I said/say/am saying.
My interpretation: said means the real past, and say means the present or a habitual thing, and am saying means the thing I am saying now or somewhere around the present.
(2) If I were in her position, I would say to John that I did a bad thing and that I am sorry.
My interpretation: She did a bad thing that offended John, and I talk about what I would do if I were she. Did means that the thing really happened in the past, not the usage about something hypothetical.
(3) If my students studied harder in my class, I would assume their parents must have scolded them the previous night.
My interpretation: They are not studying hard. I think that if they were, it is probably because they were scolded by their parents yesterday, or the night before the time I say this sentence.