@Vasile-Caraus
I can understand why \r would work in place of \R for non-Unix files in a FIND operation, but I would not use \r in place of \R in a REPLACE operation for Windows files. Truly, however, \R works fine in my extensive experience with it, and something else must be wrong in your situation.
\W and \K have no relation at all, and if indeed it works somehow in your specific application, it is sheer coincidence.
What troubles me is that you are making blanket statements such as you did, without any supporting information. So perhaps people read this thread in the future and they start mistrusting \R or \K unnecessarily.
Can you post some understandable examples of real text where \R and \K do not work right? Just saying “this doesn’t work” without more information is not helpful. I know it takes work to find specific examples and then put them together into a clear, coherent post that really seems to demonstrate a problem…but I don’t see any way around that for this case. Let’s either prove that \R and \K have issues, or let’s disprove it.