Abel-Mizraim gets dropped into the narrative of the last chapter of Genesis. It is all about mourning the dead and burying them (rather than allowing blood to cry up from the ground). Also, immediately after the name is mentioned, we have the brothers approaching Joseph, fearful of revenge.
But Joseph is forgiving, and thus he is used at the end of the story to resolve problems that started early on in Genesis.
not the same word or name
Abel – is hebel, meaning empty or vanity
abel in abel-mizraim is a totally different word, meaning green or grassy; a meadow by virtue of a stream or brook
No, actually, abel means “mist” and Ecclesiastes needs to be re-translated. (Works a lot better with “chasing the wind” as a bonus.)
And the internal evidence doesn’t suggest that it is simply green or grassy. Genesis 50.11:
Abel-Mizraim means, according to the narrative, “mourning of the Egyptians.”
But beyond that, even if it was a totally different meaning it would still be impossible for any Hebrew Reader not to connect the end of Genesis with chapter four. there can be no doubt that it was intended to suggest a connection with Abel–this is a source that agrees with you in general about “meadow.”
So I don’t think your point means there is no connection. Whatever abel-… comes to mean in later history it is the end of a giant inclusio here with Genesis 4 and it is associated with mourning for the dead in the text.