CSS style definitions for H tags and other related font tags. Some theme makers just skip the definitions they do not use, causing small issues like that.
As for Meta Language you mean this: https://www.w3.org/International/questions/qa-http-and-lang ?
That should already have been set, but I am not sure in what file it is now, used to be the header files like this one: https://github.com/PHPFusion/PHPFusion/blob/7.02.07/themes/templates/header.php
Not sure where it is now...ah, here: https://github.com/PHPFusion/PHPFusion/blob/9.01/themes/templates/header.php but that one has no meta info. Guys where did you put it?