\override TimeSignature.style = #'mensural
\override KeySignature.glyph-name-alist = #alteration-mensural-glyph-name-alist
\override Accidental.glyph-name-alist = #alteration-mensural-glyph-name-alist
\override TimeSignature.style = #'mensural
\override KeySignature.glyph-name-alist = #alteration-mensural-glyph-name-alist
\override Accidental.glyph-name-alist = #alteration-mensural-glyph-name-alist