[Parody]

Realm Works says that the style is only going to affect Text Snippets, Notes, and Journals right above the setting. You can see it in your first (way too wide!) image. :)

I thought initially that Realm Works might be at least partially keying off your system settings for some or all of the headings, but it doesn't seem to be doing that. Letting you (eventually) set the font and color for the headings seems like a reasonable feature request. Perhaps this would be a per-user feature rather than a realm setting, as the headers are different in the web client previews we've seen.