That is probably because MM lists the fieldname for content as ’content’ (see mm.inc.php line 94).
What you can try to do is to add another line in mm.inc.php after line 94 with
'bodycontent' => array('fieldtype'=>'textarea', 'fieldname'=>'ta'),
(this way you’re not messing with anything else)
and then use
mm_requireFields('pagetitle,bodycontent,tveventStartDate,tveventEndDate,tveventVenue,tveventAddress', '3,4,6', '10');
Just be aware that if your using an RTE such as tinyMce you will not have the content field highlighted if it’s empty. This may also be counter-intuitive... The content field may contain html tags and still produce an empty page... mm_requireFields will not pick that up!