No veneration is an act. Contumacoous refusal while aware that she is due it is another matter. Here is a good explanation:
“In every age the Church has drawn a fundamental distinction (which, on account of its importance, should never be overlooked) between formal and merely material heretics, and her penal legislation was directed solely against the former category. As the open and obstinate rebellion of a Catholic against the Divinely instituted teaching authority of the Church, formal heresy still remains one of the most grievous sins. Material heresy on the other hand, i.e. an error in faith entertained undesignedly and unconsciously, is in itself neither sinful nor punishable, except where the error is itself inexcusable. In excusable error are all who possess subjectively the firm and honest conviction that they have the true faith of Christ, thus including the vast majority of non-Catholics, who were born and educated in their particular form of belief”