The question Do tenses in a time clause never back-shift in reported speech? (which I'll call The Backshift Question or TBQ for convenience) has an answer that could be considered canonical for back-shifting in reported speech questions. I've just referred someone to that answer and voted to close their question as a duplicate of TBQ.
In doing so, I found that TBQ was closed as "not a real question", or in greater detail, "This question is ambiguous, vague, incomplete, overly broad, or rhetorical and cannot be reasonably answered in its current form."
After looking at Shoe's answer, I consider the question unambiguous, precise, complete, of useful breadth, genuine, and reasonably answered in its current form. In short, I submit that it is a real question and I would like to drum up some support to reopen it, with a view to making it a canonical Q&A for back-shifting in reported speech questions.
Here is a sample canonical ELL post. I haven't found an equivalent for ELU. The ELU community seems to be able to find good examples for many recurring questions, but with the recent comments in ELUm about the number of low-quality ELU questions, I'd like to explore the idea of gathering a collection of canonical answers and presenting that list in the Ask Question page.
Update (Thanks @Shoe) Here is a more comprehensive post to serve as a canonical answer for back-shift questions.