I did a couple of date changes on my (not yet started) ex-CAI DONE4 through Qantas twitter - simple and efficient (although a bit slow - it basically took the whole day).

QF says that there is no D space on JL despite EF showing availability. It seems to me that in practice one needs I availability on JL, at least this seems to match what QF sees.

The agent mentioned - without me asking - that itinerary changes will not be permitted on ex-CAI bookings, only date changes. Before departure I understand this since there is no longer a QF fare filed ex-CAI, but after departure this would go against the fare rules... in any case it seems that all OW airlines got the same memo.