A lot of ideas!

I'm fine that you're making stuff up as you go along--so I am! It's all good :)

Here's an idea on getting back to Renna that I got after reading all of your ideas:

It would be difficult to enlist the deer jinni's help directly because she's the slave to the caravan leader, and I can't see him turning around for anything. Our characters could do something daring in freeing the deer jinni and running away together (but that would strand the rest of the caravan in the middle of the desert).

So, how about this: If Curdle can create a sand golem, then perhaps he can also move relatively swiftly through the sand as said sand golem and carry Miria with him. Miria could probably find a compass from one of the many merchants in that caravan (if a compass exists in this world?) and get the deer jinni to point them in the right direction, or the deer jinni can make/give them a compass-like device that will help guide them back.

The only missing detail would be how to get Miria to want to give up all her stuff (basically her livelihood) to go back to Renna in the first place. Hmm...