Yes, I regularly use this snippet to set the document fonts. I think I learned it from Abraham Lee. IIRC, Frescobaldi also pasted it with the menu entry Tools > Document fonts …
What is the new and correct command? What Frescobaldi gives me? \paper { #(define fonts (set-global-fonts #:music "emmentaler" #:brace "emmentaler" #:roman "TeXGyre Schola" #:sans "TeXGyre Heros" #:typewriter "TeXGyre Cursor" #:factor (/ staff-height pt 20) )) } Cheers, Joram