Tim,
I've worked on multiple APIs in the 50+ years I've been programming (including as an IBM employee) on everything from MS-DOS 1.0 to mainframe operating systems like MVS.
Yes, few applications interface directly with the kernel. But the API consists of two parts - the interface and the implementation.
The interface is what the applications see. The implementation is how it interacts with the kernel and other resources. A change in the kernel can definitely change the implementation (which is why you have version-specific libraries).
But sometimes the changes in the kernel can't be covered by the implementation without changes to the interface. And yes, it does happen which is why application sometimes have version specific libraries.
So you can't say that changes in the kernel do not affect applications. They definitely can. That may or may not be the problem here but not knowing the reason for the rejection the biggest thing I see between being able to download or not is the kernel version.
Jerry, AI0K