I didn't mean to suggest that the Star was the first commercial computer that offered multiple fonts. I picked the Star because it came before the Macintosh there were good pictures of it available. I believe that the Alto also had a font that set a typeface in cursive, and even came with its own font editor, but I'd have to look harder to find videos or pictures of that.

I think you were correct to identify the Star (or at least the prototype of it), The article on the history of Smalltalk that was posted yesterday gives a date of 1972 for the first Xerox PARC font editor.