Xiaomi MI 4LTE-CU Russian Firmware

Experienced flashers tell me, I have not done this myself more than once! Comrades brought Xiaomi MI 4LTE-CU as a gift from the Celestial Empire, but they say you just need to reflash it, they themselves do not kick in the tooth, but they say that it is necessary :) I thought at first that because of the Chinese language, but no. Calmly chose Russian from the menu. I don't know about the network yet, I won't say anything, there is no micro-SIM in use. Actually, the question is whether it is necessary to reflash it at all if everything works? Or is there something for which you need to do this?
PS Android version 4.4.4. KTU84P version MIUI 7 5.12.11