我想您正在get_query_template() 功能：

    /**
     * Filter the path of the queried template by type.
     *
     * The dynamic portion of the hook name, `$type`, refers to the filename -- minus the file
     * extension and any non-alphanumeric characters delimiting words -- of the file to load.
     * This hook also applies to various types of files loaded as part of the Template Hierarchy.
     *
     * Possible values for `$type` include: \'index\', \'404\', \'archive\', \'author\', \'category\', \'tag\', \'taxonomy\', \'date\',
     * \'home\', \'front_page\', \'page\', \'paged\', \'search\', \'single\', \'singular\', and \'attachment\'.
     *
     * @since 1.5.0
     *
     * @param string $template Path to the template. See locate_template().
     */
    return apply_filters( "{$type}_template", $template );

您提到了自己的自定义插件。因此，如果要覆盖hello-cat 自定义分类法的术语，在插件中使用自定义模板，然后可以在根插件文件中尝试以下操作：

add_filter( \'taxonomy_template\', function( $template )
{
    $mytemplate = __DIR__ . \'/templates/custom.php\';

    if( is_tax( \'some-custom-tax-slug\', \'hello-cat\' ) && is_readable( $mytemplate ) )
        $template =  $mytemplate;

    return $template;
} );

/wp-content/plugins/my-plugin/templates/custom.php