I spent significant time talking to "deep techs" at amazon about the broken eink header file issue (you cannot use the eink header files if you want application programs to run on both 5.0.x and 5.1.x firmware). My solution was to copy the structures and rename the one that is "broken", so I can use both structures needed to support different firmware MINOR versions.
They say they will "get back to me in a couple of days" (exactly what they said when I wanted more than just verbal approval to distribute partition images with my debricking solution -- but their legal staff never did get back to me with written permission).
We shall see... Meanwhile, I stopped using eink header files, as you can see in my gmplay source code. The structures add a significant number of lines of code to my program even though I compressed them.