If u flash Chinese version of 12.1.5 u will only able to flash octavi OS Android 11.no other rom will boot.u must have eu 12.1.5 version of miui 12 Android 11 to boot this.ur recovery version is correct.use eu global 12.1.5 vender.otherwise rom want work
1install twrp 1206 as mentioned u above
Format data yes
Transfer eu global 12.1.5 miui 12 Android 11 to ur phone with twrp internel storage process.
After flash again format data yes(don't boot miui without wiping data)
Than reboot to twrp
Than reboot system(miui)
Let completely boot miui stock rom
Than enter twrp recovery
Transfer 404 rom from pc
Wipe data,dalvik,and cache (don't wipe data from advance wipe)wipe from first menu.
Install rippa 404 or any Android 11 rom from this process.no need any wiping after install
Reboot and enjoy.
,.,#so miui cn 12.1.5 vender want work for many Android 11 rom only octavi OS will boot.so use miui eu global 12.1.5
Here is the link
Download GApps, Roms, Kernels, Themes, Firmware, and more. Free file hosting for all Android developers.