Its a hack, you will not be able to lock the bootloader and neither will you be able to flash the official global ROM but I understand you will be able to put the EU Rom on but you must not try to lock the bootloader
I don´t want to lock my bootloader, i want to have a custom rom , be it Stable or Beta it needs only to be functional in every way .
Also i have already had this rom on my phone Author: MIUI Official TeamVersion: V9.5.13.0.OEAMIFA (MIUI9) Size: 1.6G with an Unlocked bootloader and then i put twrp back in after formatting and The EU forum´s Beta also Globerom has been a guest on phone so i am not too worried.
The Mi8 is still new and has a lot of developing to enjoy, hopefully you´ll be able to profit from the same.