So someone has released what appears to be a fully working DTH for the Aqara Curtain Motor:
I guess I missed it, but this DTH uses the Window Shade capability instead of Door Control.
Also, the command to set a partial open / close “level” is in there, and it’s sent to cluster 000D / attribute ID 0055. I asked the author how s/he figured that one out, because I was not able to find any documentation on the Zigbee commands despite a lot of searching.
I’d be very curious as to whether it changes the state from open → partly open → closed (and vice-versa) correctly.
Either way, that DTH is a lot more developed that what I’ve started, so you may want to work with that author in testing.