I've just released version 0.10.8 of rEFInd, and I wanted to highlight the fact that I've changed "OS X" to "macOS" in some on-screen messages, including the name given to the primary macOS boot loader. This in turn means that if you have a refind.conf file that uses the string OS X in its default_selection, you may need to change that as well to get the desired (former) behavior.

See the revisions page of the rEFInd documentation for more on this release.