I'm so sorry that you had this experience. Of course it's appropriate to describe it here. Where else will you find people who will understand what you went through?
My experience is that most of the FA's and other passengers, especially DYKWIAs, don't understand what it means to be unable to use your CPAP. Since sleeping without it is actually dangerous as well as painful for many people with sleep apnea, it would be helpful if FAs received some training in this area. Assistance in finding a way to use it would be a reasonable accommodation, especially when IROPs are involved. I'm sure that you planned your original bookings to allow you to use it on these long flights. After this frustrating experience, coupled with poor sleep, I think you did an awesome job of posting facts rather than merely a disjointed rant.
There seem to be 2 points to your post:
DL agents need more training in managing complicated rebookings.
DL staff need more training in accommodating disabilities.
I agree with both.