sure you can have repeater inside flexible field.
from original docs here
Nested Loop
<?php
// check if the flexible content field has rows of data
if( have_rows('flexible_content_field_name') ):
// loop through the rows of data
while ( have_rows('flexible_content_field_name') ) : the_row();
// check current row layout
if( get_row_layout() == 'gallery' ):
// check if the nested repeater field has rows of data
if( have_rows('images') ):
echo '<ul>';
// loop through the rows of data
while ( have_rows('images') ) : the_row();
$image = get_sub_field('image');
echo '<li><img src="' . $image['url'] . '" alt="' . $image['alt'] . '" /></li>';
endwhile;
echo '</ul>';
endif;
endif;
endwhile;
else :
// no layouts found
endif;
?>
basically it is nothing very special. it is just a (repeater) loop inside a (flexible content) loop
