I’m on High Sierra 10.13.6, and when I add the H2 button to the touchbar, it appears to be mapped to the Heading 3 style; when I add and use H3, it changes the text to Heading 2 style. Both issues can be confirmed by using the buttons to apply the style, and then looking in the Format > Style submenu to see what has actually been applied. Not a major inconvenience, as I am just purposely using the opposite one to trigger the style I’d like.
Thanks for the great app!