bb_func_stats.php
line 92: 'num_posts' should be $dbUserSheme['num_posts'][1]

It should be:

elseif($lst==2 && $cols=db_simpleSelect(0,$Tu,$dbUserId.', '.$dbUserSheme['username'][1].' ,'.$dbUserSheme['num_posts'][1],$dbUserId,'!=','1',$dbUserSheme['num_posts'][1].' DESC',$makeLim)){

because you could specify this field in $dbUserSheme

Thanks, we will fix it in the next release when it will be ready to go out.

Is this something we should do before the next release? What does the bug do?

This bug is very rare, it only would work if you rename 'num_posts' column. I think nobody does this so it is just an "improvement" issue.