Change level name and page title for a specific level checkout

custom-level-text-per-level-id.php

<?php

function my_custom_level_cost_text( $translated_text, $text, $domain ) {

	switch ( $translated_text ) {
		case 'Membership Level':
			$translated_text = __( 'My Membership Level Name', 'paid-memberships-pro' );
			break;
	}

	return $translated_text;
}

function my_custom_checkout_text() {
	global $pmpro_pages, $pmpro_level;

	if ( is_page( $pmpro_pages['checkout'] ) && 22 === intval( $pmpro_level->id ) ) {

		add_filter( 'gettext', 'my_custom_level_cost_text', 10, 3 );
		?>
	<script>
		jQuery(document).ready(function () {
			jQuery('h1.entry-title').text('My Custom Page Title');
		});
	</script>
		<?php
	}
}
add_action( 'wp_head', 'my_custom_checkout_text' );