Not all of our fonts support Macron characters. Unfortunately, our Support team does not have a list of fonts that work with Macron characters, it will be trial and error. Additionally, some fonts have limited support and may not work with all of the Macron characters.
Why does this need to be manually enabled?
We've found that the extra characters in the font your site uses can make your site load slightly slower. To make sure Rocketspark runs nice and quickly for everyone we don't have this enabled out-of-the-box.