filter-tec-month-list-url-links.php

// Whenever The Events Calendar displays a link to month/list view, we need to
// update it in respect of our new slug
add_filter( 'tribe_events_getLink', 'modify_month_list_link_urls', 10, 2 );

function modify_month_list_link_urls( $url, $type ) {
	if ( 'month' === $type ) return str_replace( 'month', 'calendar', $url );
	if ( 'list' === $type ) return str_replace( 'list', 'all-events', $url );
	return $url;
}