Your response reminds me so much of a trot tho. Like this is exactly their playbook and no one cares what they have to say.
Unions are not going to bring about the revolution. They are a way to get working people engaged in the class solidarity and organizing in the hopes that some join a communist party. In the imperial core there is no viable communist party. And then that party can not only criticize but can enact change because they are actually working in the unions their criticizing the decisions of.
It will always be easy to criticize wins in a trade union within a capitalist system. Maybe things do get TA too quickly maybe they don't struggle enough. But at the end of the day being the person or group of people that is constantly criticizing workers wins is not going to help people listen to you.