Sorry for answering so late…
I got two Zynthian working with the Adafruit-2.8" display. One is working in my Disco-Zynthian (see Zynthian at Maker Faire Berlin: 30.9.-2.10.2016), the other one in a Zynthian v1. Both without problems, a selfmade cable and the latest Zynthian image.
Regards, Holger