Yes you can it may work and if they are bugs due to the Android upgrade (Jb > Kk) a reboot, a reinstallation or a factory reset can resolve the problem. So make a backup of your data.
I read your message here too
http://huaweinews.com/2014/08/ascend-p6-b512/
The root access is not require for an local update with the official recovery just follow the instruction
1. Unzip the downloaded file
2. Place the Update.app inside a folder named “dload” on your SD card root directory
3. Go to Settings -> System update -> Local Update and it will install the firmware