Thanks for helping to bring this to our attention. I reviewed the API warnings in your account and, as you mentioned, it appears eBay changed the accepted values for the Heel Height attribute within the Item Specifics section since the last time you had posted the product and the value you had selected in the past was dropped because it was no longer valid.
As was explained through the support case you filed on this topic, we do not offer any tools that can be used to update Custom Item Specifics details in existing saved listings in bulk so you would need to update any of your saved listings that contain invalid values of this nature individually to avoid encountering the same issue next time you post them.
Although we do make an effort to notify our users of significant changes eBay will be making when we have advance notice, unfortunately, it is not always feasible for us to notify our sellers of every eBay change that may impact them.
Also, I looked into the ordering issue you mentioned using category # 55793 as an example and I was able to find a few attributes for which we are not displaying the eBay recommended values in the same order as they are displayed on the eBay Sell your Item form so I assume that is the behavior you are referring to.
I have forwarded the details of that issue over to our technical team for further investigation and will contact you when any additional information on that topic becomes available. It appears that our system may be forcing the values into alphabetical order, even though that does not always produce the order which makes the most sense.
We apologize for the inconvenience these issues have caused you, but we appreciate you taking the time to share your feedback with us.