I've been using the Canon SDK (Software Development Kit) for many years. Here's my theory.
When you could use the SDK to query the shutter count it would be possible to reverse engineer that function call and edit the shutter count. I think they took that function out of the SDK around 3 years ago so that hackers couldn't change the shutter count.
Its still being stored in the camera (obviously) and Canon can tell you what it is - if you ask. I think they've changed the memory location to hide it.
Magic Lantern developers have reverse engineered it - you can get it if you install their software. However I don't the 5DsR on their list of supported cameras.
yes, all functionalities are offers by the SDK officially by Canon. only the shutter counter is hidden since the version sdk2.13 ( i'm not sure).
I coded this function in assembler to read the value of the counter.
this commercial software lets you change and reset the Shot and the mirror counters!! look at this link: