Thanks guys. I actually just came up with another cute workaround.
In my master page template, I entered only “{@flowcomposer@}” into the text box I want the info, rather than “Music and Lyrics by {@flowcomposer@}” (which is what I had been doing previously).
In Project Info, in the composer value field for each flow, I put:
for Flow 1, I put “Music and Lyrics by blah blah”.
for Flow 2, I put “Music by blah, Lyrics by blah” but with a paragraph character between them
Now it is the same token for all the flows but appears with the differing word structures as appropriate, and no manual overrides.