I've answered my own question with some more reading and some messing around...

I had to run a 'foreach' that cycles through the given post's comments within the main loop.

The following code looks at all the comments for each post that passes through the loop and checks for a specific string in the comments' content. Depending on if $mystring is matched, a specific HTML ID is written to the div. At a glance, one can see which posts contain specific content in their comments. Party on.

<?php
if( have_posts() ) : while (have_posts()) : the_post(); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class('col-md-6 box');?>>
<div class="post-box article"  

<?php

$comments = get_comments( array( 'number' => 99, 'post_id' => get_the_ID() ) );

if(get_comments_number()==0) : ?>
        id="pendingcomment"
<?php else : 

    foreach($comments as $comm) :
        
        $mystring = get_comment_text( $comm );
        $findme   = 'CHANGES!';
        $pos = strpos($mystring, $findme);
    
        if($pos == true) : ?>
            id="notapprovedcomment"
        <?php elseif($pos == false) : ?>
                id="approvedcomment"
        <?php endif; 

    endforeach;
endif; ?>
>

The code could no doubt be cleaner, but is functional. Hope someone finds this useful one day.

I've answered my own question with some more reading and some messing around...

I had to run a 'foreach' that cycles through the given post's comments within the main loop.

The following code looks at all the comments for each post that passes through the loop and checks for a specific string in the comments' content. Depending on if $findme is matched, a specific HTML ID is written to the div. At a glance, one can see which posts contain specific content in their comments. Party on.

<?php
if( have_posts() ) : while (have_posts()) : the_post(); ?>
<div id="post-<?php the_ID(); ?>" <?php post_class('col-md-6 box');?>>
<div class="post-box article"  

<?php

$comments = get_comments( array( 'number' => 99, 'post_id' => get_the_ID() ) );

if(get_comments_number()==0) : ?>
        id="pendingcomment"
<?php else : 

    foreach($comments as $comm) :
        
        $mystring = get_comment_text( $comm );
        $findme   = 'CHANGES!';
        $pos = strpos($mystring, $findme);
    
        if($pos == true) : ?>
            id="notapprovedcomment"
        <?php elseif($pos == false) : ?>
                id="approvedcomment"
        <?php endif; 

    endforeach;
endif; ?>
>

The code could no doubt be cleaner, but is functional. Hope someone finds this useful one day.