I proceeded from the fact that my solution already allows mounting, since "sep=" is implemented in the Linux kernel. In other words: there is "sep" in the OS kernel, there is "sep" in the documentation, and I just updated the utilities in user space. If the Linux kernel provided another mechanism, then I would use it.
A patch to implement the already documented "sep" option for the CIFS file system.
Added support of custom option separator for the cifs filesystem.