After further investigation into this, @Shane Mc Cormack's answer isn't quite the full story...
It's true that the swaps would be resolved in the same order as the "I am a Djinn" messages that the Coven receive at the start of the game, but it is not because of the order that the Djinn was assigned, but because of the order of the players joining the game.
When roles are distributed, all of the roles for the setup are put together, randomised and then distributed to players in the order that they joined the game.
When night ends, each player's
EndNight trigger is called ,in the order that they joined the game. This is the trigger that initiates the Djinn swaps.
So to clarify about Djinns assigned after transmutes, you would be able to work out the order they occur based on the "I am a XYZ" in the opening Coven text.
This known ordering of player actions is probably undesirable, and I may look into a better way of determining the resolution of such actions, it will require discussion with the community to decide on the best I action I feel.