Replace header tags in ARVE

arve-title-replacer.php

<?php
add_filter( 'nextgenthemes/arve/title_html', 'arve_custom_title_tag' );

function arve_custom_title_tag( $html ) {

	$html = strtr(
		$html,
		[
			'<h5'   => '<h2',
			'</h5>' => '</h2>',
		],
	);

	return $html;
}