Ho, just detected that it seems we have missed to move the old "Development talk" namespace to the new wiki. More yet, it should be renamed to simpler "Talk" namespace if I'm not wrong. See, for example:
it's missing talk page, but originally had:
Also, looking for Talk pages, I've found this, recently created:
but it is incorrect (wrong namespace in that wiki) and cannot understand how it was created there (I mean, the steps performed to get it created, was using the tabs, or was manually...?).
This causes all the links to those pages to stop working (search for "development_talk") and you will find a dozen of pages with broken links, and more important, leaves out some very important documentation about the progress and decisions taken about a lot of areas.
So I'd re-add them ASAP.