The difference you should check is everywhere you have false || foo you will now get true while you get previously foo, then true && foo will now give !!foo instead of foo. Then you get the correct precedence between && / || and other operators like !.
Thanks. It's not that easy, but allowing the JS-like cast (false || 42 giving 42) + the correct operators precedence is still in the pipe for https://github.com/pug-php/js-phpize. And it's open to pull-requests if someone want to give a try.