Is a trainee nurse accidentally breaking hospital equipment considered an adverse event?

No. If the damage was caused by a nurse using a medical device in the course of her work, it is not considered an adverse event. Internship means learning by doing. After a period of study, or when the study comes to an end, we need to understand how what we have learned needs to be or should be applied in practice. Because any knowledge comes from practice and goes back to practice, it is important to put it into practice to test what has been learned.