I also wanted to write congas on a one-line staff where the high conga would be stem up above the line and the low conga would be stem down below the line. A grid is more compact than a five-line staff but still requires more space than a single line with two voices. It would be really awesome if that would be implemented in future. This wouldn’t just apply to congas but other percussion with two instruments like Maracas, Agogo bells, Bongos, Timbales, etc.