Hi @B0M0A0K
I have been using my iPad mini 4 with my Air 2S ever since the Air 2S was launched
I too get the error message that you mentioned in your original post, but every update to the Fly App since has worked seamlessly.
If you are unsure whether to trust it or not, then might I suggest that you find an open area and fly your bird without straying too far, until such time that you trust (is that the right word ??!!) the Air 2S /iPad mini 4 combination.
Good luck, but I am confident that you will be fine.
If you do decide that it is too risky, then iPad mini 5 is available on “the Bay “ at not too much more money than the 4.
Rob