Im not sure it this is the same in all version of 4images...
But in 4images 1.7.7, In order for the terms changes to show on the category edit page, i had to make this change.
For your step 7.7
In admin/categories.php
show_table_separator($lang['terms'], 2);
show_terms_select($lang['terms'], 'terms', $result['terms'], $lang['terms_array']);
show_terms_select($lang['terms_msg'], 'terms_msg', $result['terms_msg'], $lang['terms_agreement']);
Replace with:
show_table_separator($lang['terms'], 2);
show_terms_select($lang['terms'], 'terms', $cat_row['terms'], $lang['terms_array']);
show_terms_select($lang['terms_msg'], 'terms_msg', $cat_row['terms_msg'], $lang['terms_agreement']);