I do not know whether sketch is expected to work on Kobo Touch. I am just reporting that it does not show any drawings on the screen. It does however create drawing-date_time.png files (EDIT: the show only a white screen).
It is in 16-bit mode
Code:
[root@(none) ~]# fbset
mode "800x600-0"
# D: 0.033 MHz, H: 0.034 kHz, V: 0.055 Hz
geometry 800 600 800 1280 16
timings 30000000 8 164 4 18 4 1
accel false
rgba 5/11,6/5,5/0,0/0
endmode