I think it's definitely good that you updated your questions to add more explanation about why they aren't dupes and therefore get them re-opened. That's exactly how the system is supposed to work!
My only 'concern' is an entirely subjective one: although your wording is perfectly clear I personally don't like it. It's a little jarring to read that "this question is marked duplicate" when in fact it isn't any more. My view is that a question should be fully understandable and coherent on its own, without requiring someone to read or even think about previous edits or changes.
Personally, instead of this (from your first question)...
In response to this being marked duplicate:
I was aware that a biennial flight review is valid for any airplane
...I'd have written something like this:
I've already seen this related question but I don't believe it's a
duplicate because it doesn't cover the case where a biennial flight review [...]
That provides exactly the same explanation, but it still reads smoothly if the question is later re-opened, and it doesn't have any 'meta-references' to edits or status changes.