I just tested this with the reference implementation of chord pro and it completely ignores the comment directive if it's not at the start of the line (sciurius, correct me if I'm wrong). So in the reference implementation, you will actually see {c:Repeat F...} at the end of the line. So perhaps my implementation is incorrect as I'm ignoring the rest of the line if I detect a comment anywhere in it. I don't think it's valid to use the comment directive at the end of a line though. It's not meant to be used to format a small section of text to make it italic. It's meant to make an entire line italicized. The upcoming pango syntax support will allow for individual sections of a sentence to be formatted though, so I think that's ultimately what you will want to utilize.
Mike
Mike