Michael, you write: "Are we sure gedcom references to multi merges are saved and accessible?"
Yes, I'm sure. Bugs and "legacy" errors are always possible, but I'd bet that the problem you're seeing is what's described here: http://www.wikitree.com/wiki/Multiple_merges_and_redirects
Change histories get very hard to follow when A was merged into B was merged into C was merged into D, etc. You have to look at D's changes to find the link to C's changes, etc.
At some point maybe we can find a way to make these change histories clearer.
You write: "Contributors to Wikitree must be cited on the front page for their contributions."
No, this is not true.
It is not the intention of item VII in the Honor Code ("We give credit. Although most genealogy isn't copyrighted, researchers deserve credit for the work they've done.")
The intention of that bullet point is to discourage contributors from posting other people's research as if it's their own.
When you contribute your own research, you are credited as the contributor of what you write. This is all in the Changes history. You do not need to give yourself credit through an extra section on the profile page.