Kaishiwaza is tricky stuff. I believe kaishiwaza exists for two reasons:
1. To better understand aikido technique and interaction between partners
2. To protect against injury during poorly executed technique
I believe kaishiwaza is "advanced" in the sense that students should first learn to to execute a technique before they learn to reverse a technique. In general, I think a competent student can expect to be comfortable executing a technique in the 5-10 year sweet spot; there will be some who excel and some who do not excel.
I feel a good curriculum for students has plenty of technique on which to focus training efforts. Kaishiwaza can wait.