I would be careful when draining all the fluid from a CVT transmission. Whatever you do, don't flush it. I would just drain all of the fluid and put in the correct one. I doubt that the transmission will fail because you didn't put 1k miles on it after the drain and fill.

Drop the pan, clean the pan and then fill with correct fluid. 

Well, I’d go to the dealer and see what I can get out of them - the minimum I’d accept is a free full fluid drain and a refill.

after all, it’s their mistake for selling you the wrong fluid.

But although this is not something I can say for sure, I wouldn’t think you have much of case if it does breakdown. Your car doesn’t have Aisin’s half decent K114 it’s probably a K310/K311 and on those… they can claim bearing whine and other symptoms of wear are “completely normal for it’s mileage and were not caused by the fluid”

(which is kind of true, I have seen a K310 go out on an Auris at bellow 60k miles but that was a “particularly spirited driver” and it was used in city traffic - two things a CVT isn’t meant for as those cause slippage)

Swapping in a new transmission doesn’t sound like a particularly good idea - those cost many thousands and that’s a 7-8 year old car…

If damage was done, there is no way I can think of to reverse it. So let’s see how we deal with the circumstances at hand…

What I’d do is get the fluid fully extracted and refilled with the correct fluid and monitor to see that the transmission does not have any bearing whine or excessive slippage.

If the transmission is in reasonable condition, then I’d just keep using it. But keep in mind that it is a CVT so I’d avoid cases in which slippage can occur

Should have got Car Shield or some other after market warranty. But it might not cover improper maintenance.