Add labels to facets using facetwp_shortcode_html hook

<?php
/**
 * add labels above facets by changing shortcode output
 * this will apply to all facets except $exclude_types set below
 * change or remove conditional to apply this to whichever facets needed
 * wrapper can also be added
 */
add_filter( 'facetwp_shortcode_html', function( $output, $atts ) {
    if ( isset( $atts["facet"] ) && '' != $atts["facet"] ) { // check for facet shortcode
        $exclude_types = [ 'sort', 'reset', 'pager', 'map' ]; // set facet types to exclude from labels
        $facet = FWP()->helper->get_facet_by_name( $atts["facet"] ); // get facet settings
        if ( !in_array( $facet["type"], $exclude_types ) ) { // conditional to exclude types in $exclude_types
            $output = '<h3 class="facet-label">' . $facet["label"] .  '</h3>' . $output; // prepend with label and markup
            // uncomment below to add facet-wrap
            // $output = '<div class="facet-wrap">' . $output . '</div>';
        }
    }
    return $output;
}, 10, 2 );