Unfortunately, not all of the website design template title fonts have accents available. In these cases, since the fonts themselves were not originally designed with accent marks in mind, there is not an option to add them. This is also the case for many special characters such as & + @ * #.
The best suggestion we can offer is that you select another template that will accept accented letters. When previewing a new template, enter the accented letter in the title field, the click the preview button to see if the accents will appear. Learn more about selecting a template.