Where can I make requests to reopen questions on the Super User main Stack Exchange?
Right here on Meta Super User. This is what the tag guidance says for reopen-request:
Requests to have closed questions reopened by community or a moderator. Please include arguments – why should the question be reopened?
I had such a request closed as off-topic and I don't understand why.
Your question is not a reopen request. For starters, you don't give an actual request (or reasons) to reopen it. Second, is the fact that the question is titled "Heavy Handed Moderation", and you spend the majority of the question body calling out a moderator's actions as "unwarranted pedantry". You added a sentence requesting it get migrated (not reopened, btw) as a secondary point to the rant - after it was already closed.
For it to be a request, you should
- focus less on the actions taken thus far*
- focus more on the actions you'd like to be taken moving forward.
For your specific circumstance, it would look something like this:
Please consider migrating this question to Engineering SE
I have the following question about LED screen technology [link to deleted question], which was closed as off-topic. Despite clarifying edits it remained closed, and is now deleted.
I have determined that it's on topic at Engineering SE [link to Engineering meta], and I'd like it to be migrated there. Can a moderator please undelete & migrate it there instead?
This is not a guarantee that the request would be handled the way you want it to be: It is possible that the requested action will be denied, and you should be prepared to accept that outcome.
Of course, all this is a fairly moot point, considering you can simply repost it on Engineering, as covered by your other post on the matter.
* This includes not calling out & judging individual community users or moderators for their actions.