If COPPA is not used in phpBB2, it is set in phpBB3 and vice-versa.

In phpBB2, if an address is entered in "COPPA Mailing Address," it is assumed that COPPA is to be used.

The phpBB2 convertor has

'coppa_enable'			=> 'is_empty(coppa_mail)',

If no address is entered, is_empty returns TRUE, which sets COPPA in phpBB3 to be used.
If an address is entered, is_empty returns FALSE, which sets COPPA in phpBB3 to NOT be used.

What is needed is a function such as not_empty.

function phpbb_not_empty($var)

{

	return not(is_empty($var));

}