I mostly run v4.9 as of now. Other higher kernels are also fine …
Seems some went wrong on your end. Now you have a partial updated system with a broken package manager. However, I don’t know any libcuc.so.58. Typo? Can you link me a post?
The answer is already given in every announcement. Always check if your mirror had synced with our service.
On encrypted systems it is always not good to use the force switch. I always recommend to check the file conflicts using
pacman -Qo <path/to/the/conflicting/file>. This will give you the package name including that file, or an answer that you had installed a file without using a package manager.