Actually, I encounter chord problems more often with the MIDI rendering. For instance, the Concertina.net converter treats 7th chords (like A7) as major 7th (Amaj7 or AM7) chords instead of as dominant chords (minor 7th). Mind boggling.

I also find that Folkinfo's converter better handles layout, voices, repeats and part ordering. In fact, I'm quite impressed with what the converter CAN handle. One just has to experiment a bit to figure out which "extended" features one can use.