When questions are merged, the 'donors' cease to become questions any longer, they become 'stubs' that lead people to a canonical question and answer. People often ask the same question in completely different ways, these 'stubs' show up in search results and lead people to the answer that they want, and probably what they should have been searching for all along.
The first case you linked is exceptional. There, the 'stub' was a near carbon copy of the question it actually leads to, almost as if someone hit a submit button twice. I've since deleted it, as there's no real value in the context of the purpose that I described.
There's really no sense in doing much to fix them up since there's no hope of them being re-opened, and they clearly lead to better information. If a stub were edited to the point where it no longer was a duplicate of the question it points to, it should have just been a new question altogether.
Additionally, some of the 'quirks' within stubs (such as terminology like 'jQuery variable') actually help rather uninformed searchers turn them up, leading to what we hope is a bit of an education on the matter. It's better to just lock them as they were when the merge took place, which is why it happens automatically. There's also no reason for them to continue to receive votes, they're just road signs.
If you find one that you think is very problematic, or points to a question that no longer exists, flag as you did and forget about it. On the scale of importance when it comes to the time you want to give to the site, these are below the bottom.