Matrix -> Super Table - > Matrix
Firstly, you'll need to change:

{% for row in superTableBlock %} to {% for row in block.superTableBlock %}

So you can reference the Super Table field within your out Matrix field.

You also don't need to loop through {% for block in row.superTableBlock %}

I can't tell if you're looping through the inner Matrix field. Have you tried:

{% for block in entry.matrixFieldParent %}
    {% if block.type == "sectionBuilder" %}
        {% for row in block.sectionBlock %}
            {% for sectionLayout in row.sectionLayout %}
                {% switch sectionLayout.type %}
                    {% case "contentBlock" %}
                       {{ sectionLayout.sectionGrid }}
                    {% case "articlesFeedBlock" %}
                       {{ sectionLayout.sectionBackground }}
                {% endswitch %}
            {% endfor %}
        {% endfor %}
    {% endif %}
{% endfor %}