Arrow notation and transposition for quarter tones

If you use arrow notation for quarter tones, and distinguish a raised natural from a lowered sharp, you can define extra note-names to enter notes with these distinct alterations.

You list all the pitch-changes that your notation distinguishes, and then choose what symbols to use for each pitch pitch-change. Transposition uses your defined pitches: \transpose bes, c \music takes the difference between your pitch bes and your pitch c and shifts every pitch in \music by that amount. If the resulting pitches have an alteration with an entry in the glyph-name-alist, that symbol is printed. A missing entry generates a warning. You can put as many alterations in glyph-name-alist as you like.