How can I write (Em9) chord ..there is no 9 to select
We are working on that. Basically, 9 is 2, the chord editor does not yet extend beyond 7+ and we’ll add that (most notably 13, which is the same as 6, but one octave higher). Add 7, and you get 9 for 2, and 13 for 6 
…and power chords for guitarists (or neutrals non-dur/-moll ) if touching that area 
Maybe a free text-box would solve this for rare chords