Hello,
I have used the xiaomi.eu roms for months now, and I liked them a lot. But...
Yesterday I flashed the mi5 6.12.8 from this post, after updating TWRP and doing all that's written, and It's not what I want: no sim card recognised, phone app always crashing, overall too beta for me. I tried to go back to the last stable from this post, to the official global developer, even tried through miflash. All roms I tried bootloop, so my choice is between a rom with no mobile connection and unusable for the continuous crashes, and one that bootloops.
I know for sure lots of people are having issues with 6.12.8 on mi5, but I haven't found solutions.