I have a page in English and the same one in French, however the title cannot be translated to French, so even though the whole page is in French the title is in English. The titles are the same on the French and English versions. Is this considered to be duplicate content? If so, should I just change the title of the English page in my CMS?
Problem with duplicate content becomes important when most of the pages content exactly the same content on several places, but Google as a ratio of allowed duplicate content that is allowed for example for the copyright zone, the menus, etc.
The main problem with untranslated titles is that you will have a lower Click-Through-Rate on French Queries and you will have a lower ranking on French keywords that could have been set in the title. It is also bad for UX (User Experience). Finally, but that is in my opinion a smaller problem, Google might decrease the ranking of the two pages for duplicate titles since it is bad practice, but this would have a smaller effect than the three aforementioned points.
So, to answer your last questions: yes and no. You need to have distinct and translated titles for your English and French page.