The problem here is that the comment form on pages and posts will appear after the comment form. This is part of the responsive nature of the theme, so that the content in the sidebar appears above the comments on smaller devices.
And so the sidebar is intended not to be full of too much content. The focus in this theme is what’s in the post or page.
Certainly the large wiki list would not be great when the browser gets smaller and probably not best put in this particular sidebar.
Does the widget for the wiki have a drop down list version? That may look better and bring the comments form further up the page.