Expected/Wanted: Corrected message appears as a new reply in the same thread, in the same position (order relative to same-level replies notwithstanding) as the deleted post had been.
it isn’t the same post, it is a new post showing as a new reply with the same (edited) content as the post you deleted. Behavior is as expected to me (and is as intended), ad is also how mastodon did it.
You would need to edit the post instead, which will give you your preferred behavior and is the current accepted/preferred method to change a post I believe.
edit: oh I think I misread - so the post isn’t a reply any more and is a stand alone post?