I use Pages as my main word-processing application and regularly have to type in both English and Greek. I use either Times New Roman or Hoefler Text in English and GFS Porson for Greek. Is there a way to automatically trigger a specific font (in this case, GFS Porson) anytime I switch over to the Greek keyboard?
Pages doesn't itself have a way to do that exactly, but the app Nisus Writer does, via preference settings.
In Pages I'd recommend creating "styles" for Greek and English in your preferred fonts. Styles can be attached to keyboard shortcuts.