How to display comment meta under each comment content

As an easier alternative, you can use flexbox to reorder the comment items:

.comment-list article {
    display: flex;
    flex-wrap: wrap;
}

.comment-list .comment-meta,
.comment-list .comment-content {
    flex: 0 0 100%;
}

.comment-list .comment-meta {
    order: 2;
}

You will need get_comment_meta to pull that information from the database. You will need to know the metakey. If you don't have that, you will have to search the theme/plugin that generates the metadata for the occurence of add_comment_meta to find it.

Where to hook depends on how your theme is listing the comments. If it simply uses wp_list_comments there is no filter to simply attach the metadata. You will need to change the callback argument using the wp_list_comments_args filter. Then you can make a callback function that specifies which comment and meta data to display and how (learn more).