This is a help for those like me who had questions about bootloader in mi4c. In my case i bought it in *******, it came with that strange version of miui 18.104.22.168, every phone that brings that strange version have unlocked bootloader, just install the developer rom 6.1.7 in en.miui.com, PLEASE INSTALL THIS ONE(6.1.7) , because the roms after already brings the bootloader locked. Once you have the developer 6.1.7 installed, you just need to install TWRP, and then install the xiaomi.eu libra version for mi4c, that is much much better than any other roms, i am a portuguese user and i am pleased with it! My mi4c is much more smooth than with the original stable rom! I hope this thread help those who want to install it and dont know if it is possible! If your phone never had a stable china rom superior than 7.0.16 or the developer superior than 6.1.7, you can instal safely the twrp and the xiaomi.eu rom.