[acjohnson55]

The note between fa and sol is fi or se, depending on if it's the sharp 4 or flat 5 functionally. Sharp 4 would be most common, since it comes up as the leading tone of the dominant's key, e.g. in an secondary dominant, like V7/V.

But I guess you could get the flat 5 if you did the tritone substitution of the secondary dominant of the IV, which would be bV7.

[thaumasiotes]

I know that fa sharp is fi and so flat is se. The point of my comment was (1) that I was having difficulty labeling the note in question, meaning I couldn't use either name; and (2) that the heuristic "use the enharmonic that doesn't interfere with other nearby notes" doesn't work, because the notes a half-step away in either direction are both in use.

[acjohnson55]

Oh sorry, I misread your comment and that you were referring to a specific piece. Are you talking about the vibraphone part in the beginning? If so, I think you did it right. I wouldn't consider those little dips of the top note to be a chord change, but just a neighbor tone (https://en.wikipedia.org/wiki/Nonchord_tone#Neighbor_tone). So I'd treat it melodically and just put it on the adjacent line, with whatever accidental works. Like you did!

And then I think you may be talking specifically about measure 11. I'm pretty rusty on my analysis, but it seems like it's the iv7 chord, but starting and ending with a chromatically raised root, which is slick because it acts as a passing tone from the i chord in measure 10 and the V in measure 13. I would probably do Gb -> F -> Gb, because the F is the chord tone, and the Gb is the nonchord ornament. But yeah, probably doesn't really matter!