You have to define a .static.name for each window, or provide a name when calling addWindows(). See examples here: https://www.mediawiki.org/wiki/OOjs_UI/Windows/Window_managers
The fact that OOjs UI lets you do this wrong is a bug, though (and we have some documentation pages that provide bad advice). I filed https://phabricator.wikimedia.org/T149807 about it.
Also, you should move your definition of ArchiveSection and CommentInSection classes to top level (they're inside an event handler now). Right now your code actually redefines these functions/classes every time the user clicks the buttons. So after the second time the (for example) "add comment" button is clicked, `commentInSection.constructor` will no longer be equal to `CommentInSection`. This could cause hard-to-debug problems in the future.