Redirect Community Events' login form to your own login form. Requires Community Events 4.4.7 (June 1, 2017) or later.

functions.php

<?php
/**
 * Redirect Community Events' login form to your own login form. Requires Community Events 4.4.7 (June 1, 2017) or later.
 *
 * You may want to consider redirecting successful logins to the Community Events' Add New form or My Events list.
 * For prior versions of Community Events, reference https://gist.github.com/cliffordp/75d45b7508b881abdf0b60d3aa677ecf
 *
 * From: https://gist.github.com/cliffordp/c78a2ca22a6f231abb5754540a5f86f4
 *
 * @link https://developer.wordpress.org/reference/functions/esc_url_raw/
 * @link https://secure.php.net/manual/en/function.filter-var.php
 * @link https://developer.wordpress.org/reference/functions/wp_redirect/
 */
function cliff_ce_login_redirect_to_custom_login_url() {
	// !!! enter your full URL here (including HTTP or, ideally, HTTPS) !!!
	$redirect_to = '';

	$redirect_to = esc_url_raw( $redirect_to );

	if ( false === filter_var( $redirect_to, FILTER_VALIDATE_URL ) ) {
		return;
	}

	// 301 is permanent. 302 is temporary.
	// https://en.wikipedia.org/wiki/List_of_HTTP_status_codes#3xx_Redirection
	// function's default is 302
	wp_redirect( esc_url_raw( $redirect_to ) );
	exit;
}
add_action( 'tribe_community_before_login_form', 'cliff_ce_login_redirect_to_custom_login_url' );