This plugin (available in b2evo 6.7) will automatically adjust the headings of all posts and/or comments to make them consistent.
For example, if you have one post containing
<h1> sub-headings and another containing
<h4> sub-headings when your normal sub-headings should be
<h3>, this plugin will adjust all of them to
<h3>. Of course, that is for the highest level of sub-headings. If you use sub-sub-headings, they will be adjusted down to