Is it a religious error that invalidates the effectiveness of charitable works to photograph and publish the activities of the charitable society in newspapers for publicity, and for girls to mix with men during society meetings and project implementation?

Allah has commanded us to do good and cooperate in it, and He has warned us against division and cooperation in sin and aggression. Your work is an act of goodness and obedience, so be keen that it conforms to the Sharia. It is not permissible to mix non-mahram boys and girls at any time. As for photographing the association's activities for documentation purposes or to spread goodness and invite to it, there is no religious impediment to it, provided that what is being photographed is permissible to photograph.